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A frequency in hertz, and no decibel figure

ACME Tornado Slimline No. 636, orange, pealess, three air outlets

The one listing on this shelf that states outright it has no ball inside, and the one that publishes no decibel figure at all — it gives a frequency, up to 4000 Hz, and leaves the loudness claim as words.

ACME Tornado Slimline No. 636 whistle in fluorescent orange on a key ring

ACME Tornado Slimline No. 636, orange, pealess, three air outlets

The one listing on this shelf that states outright it has no ball inside, and the one that publishes no decibel figure at all — it gives a frequency, up to 4000 Hz, and leaves the loudness claim as words.

Pealess or pea design
Pealess — stated; the maker writes that this model has no ball, unlike a conventional trill whistle
Material
Not published on the listing — the body is described as small, thin, light and fluorescent orange, with no polymer or metal named
Dimensions
Not published on the listing
Stated weight
Not published on the listing — described as particularly light, with no gramme figure
Published decibel figure
Not published on the listing — the maker publishes a frequency instead, tones of up to 4000 Hz, and calls the whistle one of the loudest in the world
Distance quoted at
Not published on the listing — the maker states a carry still audible at kilometres, which is a claim about range and not a distance attached to a measurement
Attachment type
Key ring — stated; the maker describes it fitted to trekking rucksacks and buoyancy aids
Amazon reference
B000SE9NMY (same reference on 6 Amazon marketplaces)
EAN
0717668126361
  • One of only two listings in this hub that state in plain words whether there is a ball inside, and it states there is none
  • Publishes a frequency, up to 4000 Hz, which no other listing on this shelf gives at all
  • No decibel figure at all, on the one specification the other six listings lead with

Best for: Someone who wants the pealess question answered on the page rather than inferred, and who is content with a frequency in place of a loudness number.

≈ $8 / £5 / 8 €
Check price on Amazon

Specifications

Pealess or pea design
Pealess — stated; the maker writes that this model has no ball, unlike a conventional trill whistle
Material
Not published on the listing — the body is described as small, thin, light and fluorescent orange, with no polymer or metal named
Dimensions
Not published on the listing
Stated weight
Not published on the listing — described as particularly light, with no gramme figure
Published decibel figure
Not published on the listing — the maker publishes a frequency instead, tones of up to 4000 Hz, and calls the whistle one of the loudest in the world
Distance quoted at
Not published on the listing — the maker states a carry still audible at kilometres, which is a claim about range and not a distance attached to a measurement
Attachment type
Key ring — stated; the maker describes it fitted to trekking rucksacks and buoyancy aids
Amazon reference
B000SE9NMY (same reference on 6 Amazon marketplaces)
EAN
0717668126361

What this listing puts on record

The Tornado Slimline No. 636 in orange: a whistle the maker states has no ball inside, with three air outlets, described as one of the loudest in the world, reaching tones of up to 4000 Hz, small, thin and light enough for a key ring, and waterproof.

A frequency where the others print decibels

Six of the seven listings on this shelf print a decibel figure. This one prints 4000 Hz instead — a frequency, which says how high the tone sits, not how loud it is. It is the only frequency figure in the hub, and it is the only listing here with no decibel number at all.

The maker also writes of a carry still audible at kilometres. That is a claim about range, not a distance attached to a measurement, and it is left here in the manufacturer’s own terms.

Two numbers that answer different questions are not two grades of the same answer. What this listing gives is a pitch; what the other six give is a loudness claim with no distance behind it. Neither set is comparable to the other.

No ball inside, and the maker says so

Pealess — stated. The second bullet says in as many words that this model has no ball, unlike a conventional trill whistle, and that its volume is distributed across three air outlets.

That matters because it is the one design division this family is chosen on, and only two of the seven listings here state which side of it they fall on. A ball is a moving part; a shaped chamber is not. This maker publishes which it built.

Five lines this listing never fills

No material. The body is called small, thin, light and fluorescent orange, and never named as a polymer or a metal — one of only two listings in this hub that skip it.

No dimensions and no weight, on the listing whose whole design argument is slimness.

No decibel figure and no distance. For an object sold on being heard, the loudness claim arrives as a phrase and as a hertz reading, and never as a number with a measuring point behind it.

The maker lists where the whistle turns up: on trekking rucksacks and buoyancy aids, in refereeing, as a training whistle across several sports and as a dog whistle, and it notes that this model was once standard issue on life vests. Those are the manufacturer’s descriptions of where the object ends up. What a whistle is for, and how it is meant to be used, are questions for the manufacturer’s own instructions rather than for this page.

Availability

Selling at about 8 € on the German, French, Italian and Spanish Amazon stores when this page was checked.

It also sells on the American and British Amazon stores in the local currency, which the range above does not cover — that range counts euro stores and nothing else.

Every figure in this section is what Keepa returned on the day this page was last updated. Prices and offers change without notice.

Prices quoted in this text were read on 6 September 2026. The live price is at the top of the page.

More signal whistles

  • Bramble ten-pack of signal whistles with cords laid out together

    Bramble ten whistles with ten cords, over 100 dB stated

    Ten whistles and ten cords in one box, stated at over 100 decibels — the lowest published figure on this shelf — with no material, no size and no weight given anywhere on the page.

    Pealess or pea design
    Not published on the listing in those words — the maker states there are no moving parts and nothing to obstruct the whistle, and never uses the word pea
    Material
    Not published on the listing — no polymer, metal or finish is named in the title or the five bullets
    Dimensions
    Not published on the listing
    Stated weight
    Not published on the listing
    Published decibel figure
    Over 100 dB — stated, written as a floor
    Distance quoted at
    Not published on the listing — no measuring distance, method or standard is given
    Attachment type
    One cord per whistle — stated, ten whistles and ten cords in the set
    Amazon reference
    B072BV8TXJ (same reference on 6 Amazon marketplaces)
    EAN
    0714983185134
    • Ten whistles and ten cords in one purchase, where every other listing in this hub sells one or two
    • The maker states the whistles are fully waterproof and can float in seawater
    • No material named at all, which is one of only two listings in this hub to leave that blank

    Best for: Kitting out a group from one box, where the count and the cords matter more than a specification sheet.

    ≈ 10 €
    Check price on Amazon
  • DONGKER stainless steel dog and training whistle on a neck lanyard

    DONGKER CNC-formed stainless steel dog and training whistle, 120 dB stated

    Titled and written as a dog and training whistle before anything else, in CNC-formed stainless steel and stated at up to 120 dB — the only listing here that says how its body was made.

    Pealess or pea design
    Not published on the listing — nothing in the title or the five bullets says whether a ball sits inside
    Material
    Stainless steel — stated, formed by what the maker calls a precise CNC one-piece process, with high hardness and resistance to cold, heat and corrosion
    Dimensions
    Not published on the listing — described as a small whistle, with no figures
    Stated weight
    Not published on the listing — described as light, with no gramme figure
    Published decibel figure
    Up to 120 dB — stated, written as a ceiling
    Distance quoted at
    Not published on the listing — no measuring distance, method or standard is given; the title calls the whistle high-frequency without publishing a hertz figure
    Attachment type
    Rucksack, key ring or neck lanyard — stated as places to hang it; the listing does not say which fittings are supplied
    Amazon reference
    B0BY4SWPGS (same reference on 5 Amazon marketplaces)
    EAN
    0774827526592
    • The only listing in this hub that says how the body was formed, as a CNC one-piece process
    • Stainless steel with cold, heat and corrosion resistance all stated together
    • Written and titled as a dog and training whistle first, which is not what this shelf is read on

    Best for: A whistle bought mainly for training an animal, where the steel and the forming matter more than the size.

    ≈ £10 / 13 €
    Check price on Amazon
  • makstore stainless steel signal whistle with a neck lanyard, chain and key ring

    makstore stainless steel whistle, 54 × 10 mm, with lanyard, chain and key ring

    The only listing on this shelf that puts its size in the title — 54 × 10 mm — in 100% stainless steel, rated at max. 120 dB, and supplied with three separate ways of carrying it.

    Pealess or pea design
    Not published on the listing — nothing in the title or the four bullets says whether a ball sits inside
    Material
    100% stainless steel — stated, in what the maker calls a bamboo design
    Dimensions
    54 × 10 mm — stated in the title
    Stated weight
    Not published on the listing — described as mini size, with no gramme figure
    Published decibel figure
    Max. 120 dB — stated, written as a ceiling
    Distance quoted at
    Not published on the listing — no measuring distance, method or standard is given
    Attachment type
    Neck lanyard, stainless steel chain and key ring — stated, all three supplied
    Amazon reference
    B01MXZC828 (same reference on 5 Amazon marketplaces)
    EAN
    1909070652111
    • Publishes its size in the title, where it can be read before the page has finished loading
    • Three separate carrying fittings are named as supplied, which is more attachment hardware than any other listing here describes
    • No weight at all, on a listing whose selling point is that it is a mini size

    Best for: A whistle that has to be on a neck, a chain and a key ring by turns, with the tube length known before it arrives.

    ≈ 9 €
    Check price on Amazon

Others worth keeping in the pack

  • BROWINT mulberry silk sleeping bag liner folded beside its nylon stuff sack

    BROWINT mulberry silk liner, three cuts, 140 g and 180 g

    The only silk liner in this hub and the only one that names a mummy cut, sold in three formats of which the third is listed without a single measurement.

    Shape
    Three cuts offered — an extra-wide, an ultralight and a mummy — stated; it is the only listing in this hub that names a mummy shape at all
    Dimensions
    Extra-wide 220 × 110 cm and ultralight 220 × 87 cm — stated, with the extra-wide given as 23 cm wider than a conventional bag; no dimensions are published for the mummy cut
    Fabric
    100 per cent natural mulberry silk — stated; the maker claims it does not irritate skin and generates no static
    Stated weight
    180 g for the extra-wide and 140 g for the ultralight — stated; no weight is published for the mummy cut
    Packed size
    Not published on the listing — a tear-resistant nylon bag with a hook that clips to the liner is described, and no dimensions are given for it
    Added warmth the maker claims
    No figure. The maker states the liner suits four seasons and has a temperature-balancing effect; no number of degrees and no standard is published
    Closure type
    Not published on the listing — no zip or tie is described; a pillow cover and reinforced corners are
    Washing instructions
    Machine washable and stated to dry quickly — stated; no temperature is given
    Amazon reference
    B07YHWLB78 (same reference on 2 Amazon marketplaces)
    EAN
    0602318551245
    • The widest cut published in this hub at 220 × 110 cm, and the maker says how much wider that is
    • The only listing here that names a mummy shape, which is the shape most trekking bags are
    • The mummy cut is named and then given neither a size nor a weight, which is the version most readers came for

    Best for: A tapered bag where a square liner would bunch, or a wide sleeper who needs the 110 cm cut and will pay for silk.

    ≈ 77 €
    Check price on Amazon
  • Miqio 2in1 travel sleeping bag liner opened out flat as a large blanket

    Miqio 2-in-1 liner and 180 × 200 cm blanket

    A liner sold as two products: a 90 × 220 cm sleeve, or a 180 × 200 cm double blanket once the full-perimeter zip is opened, with the zip side chosen at purchase.

    Shape
    Not published on the listing as mummy or rectangular — the maker calls it 2-in-1 and gives a 90 × 220 cm sleeve that opens to a 180 × 200 cm blanket, and states the sleeve suits side sleepers
    Dimensions
    90 × 220 cm as a liner — stated; 180 × 200 cm opened flat, described as double bed size — stated
    Fabric
    Not published on the listing — the material is named only as Cotton Touch, and the maker states it is not cotton and dries faster than cotton; no fibre is named
    Stated weight
    390 g — stated
    Packed size
    Not published on the listing — a transport bag with a mesh panel is described so that damp can escape, and no dimensions are given for it
    Added warmth the maker claims
    Not published on the listing — the maker positions it for hot countries where even a light sleeping bag would be too warm, which is the opposite claim
    Closure type
    A full-perimeter zip that opens completely, supplied left hand or right hand and chosen at purchase — stated
    Washing instructions
    Washable, and stated to dry fast enough to be washed while travelling; no temperature and no machine or hand instruction is given
    Amazon reference
    B0744L8FKW (same reference on 6 Amazon marketplaces)
    EAN
    4260524230512
    • The zip runs the whole perimeter, so the same piece is a sleeve or a stated 180 × 200 cm double blanket
    • Left-hand and right-hand versions are offered, which matters if two are being used side by side
    • Cotton Touch is a trade name, not a fibre, and the listing never says what the cloth actually is

    Best for: Warm-country travel where a light sleeping bag would already be too much, and where the same piece has to serve two people as a blanket.

    ≈ £22 / 21 €
    Check price on Amazon
  • Naturehike ultralight sleeping bag liner rolled into its small stuff sack

    Naturehike ultralight liner, 210 × 80 cm, about 128 g

    The lightest of the seven liners here at a stated 128 g, packed to 6 × 15 cm, and the listing never once says how it closes.

    Shape
    Not published on the listing — neither mummy nor rectangular is named anywhere in the title or the five bullets
    Dimensions
    80 × 210 cm opened out — stated, and also given as 31.5 × 82.7 in
    Fabric
    Felted nylon of low elasticity, described as a velvet-like weave — stated; the stuff sack is separately given as 10D fabric
    Stated weight
    About 128 g — stated, and also given as 0.28 lb
    Packed size
    6 × 15 cm — stated, and also given as 2.4 × 5.9 in
    Added warmth the maker claims
    No figure. The maker states the liner can improve the warmth and comfort of a sleeping bag; no number of degrees is published and no standard is named
    Closure type
    Not published on the listing — a zip is mentioned only when the washing label is described, and nothing says how the liner itself opens or shuts
    Washing instructions
    Machine washable — stated, with a washing label sewn where it will not catch; no temperature is given
    Amazon reference
    B0CRKNGVS9 (same reference on 5 Amazon marketplaces)
    EAN
    6976507661300
    • A stated 128 g and a 6 × 15 cm pack, and no liner in this hub publishes either figure lower
    • Both figures are repeated in imperial as well as metric, so nothing has to be converted or guessed
    • No closure is described at all, so it is unclear whether there is a zip, a tie or nothing

    Best for: Counting grams on a summer trek, where the liner is there for hygiene and the bag is doing all the insulating.

    ≈ £17 / 17 €
    Check price on Amazon

All signal whistles