Retention hours only compare when the stated conditions match · review
A 500 ml double-walled stainless flask that publishes its capacity and nothing else the category is compared on: no retention hours, no steel grade, no mouth, no weight.
A 500 ml stainless steel flask with a stated double-walled construction and a lid the maker calls leak-proof, offered in several sizes and colors.
Six of the nine flasks in this hub quote retention in hours. This one quotes none. It says drinks stay ice-cold for hours and that coffee stays hot, and it stops there.
That matters less than it looks, because none of the nine publishes the conditions behind its hours either. But a flask with no figure cannot be put on the same line as one with a figure, however loosely that figure was arrived at.
No steel grade. 18/8 is named by four flasks here. This one says stainless steel.
No mouth diameter. Nothing tells you whether a bottle brush or an ice cube goes in.
No base diameter, no empty weight. The listing mentions running, cycling, camping and hiking; it does not say what the flask weighs before it is filled.
If the hours matter to you, this is not the listing to compare on. If 500 ml of double-walled steel with a leak-proof lid is the whole requirement, the listing does settle that much.
The American Amazon store was listing it at about $8 at the time of writing.
Every figure here is what Keepa held on the day this page was last revised. Offers and prices shift without warning.
Prices quoted in this text were read on October 23, 2026. The live price is at the top of the page.
A listing is not an offer: the reference exists on these stores, availability changes daily.
| Capacity | 500 ml — stated in the title |
|---|---|
| Wall construction | Double-walled insulation — stated; the listing does not use the word vacuum |
| Steel grade | Not published on the listing — the flask is called 100% stainless steel, with no grade named |
| Hot retention | Not published on the listing — the listing says drinks are held hot or cold, with no number of hours |
| Cold retention | Not published on the listing — drinks are stated to stay ice-cold "for hours", which is not a figure |
| Retention conditions stated | Not published on the listing — no retention figure is published, so there are no conditions behind one |
| Mouth diameter | Not published on the listing |
| Lid type | Not published on the listing — a secure leak-proof lid is claimed, and its mechanism is not named |
| Seal availability | Not published on the listing |
| Base diameter | Not published on the listing |
| Finish | Not published on the listing — several sizes and colors are offered, and no coating is named |
| Empty weight | Not published on the listing |
| Amazon reference | B0CYSTYSHH |
| EAN | 3701152106301 |
The listing does not say. It claims drinks stay ice-cold for hours and that coffee stays hot, and it gives no number against either. Every comparison in this hub starts from a published figure, and this flask does not offer one.
That is a question about your route rather than about the flask, and the maker publishes nothing else to weigh it against — no empty weight, no mouth diameter for refilling from a wide source. The capacity is the only figure on the page.
No. Not published on the listing — the flask is called 100% stainless steel, with no grade named. What the listing does publish instead is the wall construction: Double-walled insulation — stated; the listing does not use the word vacuum.
7.2/ 10
The flask that publishes a capacity and stops. Everything the hub compares on is left blank, and that is worth knowing before it is compared with anything.
Close prices, same category: comparable camping gear. We keep only the specifications all of them publish, because a column with gaps compares nothing.
| Model | Price | Capacity | Wall construction | Steel grade | Hot retention |
|---|---|---|---|---|---|
| Mont-Clair 500 ml double-walled flask | $8 | 500 ml — stated in the title | Double-walled insulation — stated; the listing does not use the word vacuum | Not published on the listing — the flask is called 100% stainless steel, with no grade named | Not published on the listing — the listing says drinks are held hot or cold, with no number of hours |
| IRON °FLASK 32 oz narrow mouth | $9 | 32 oz — stated, about 950 ml. The maker’s own wide-mouth listing states that only its 14, 18 and 22 oz versions fit a car cup holder, so a 32 oz bottle from this range does not | Double wall insulation — stated, and credited with keeping the outside sweat-free with cold drinks. No vacuum is named in so many words, and no layer count beyond two | 18/8 stainless steel — stated as premium, BPA-free and non-toxic, and stated never to leave a metal taste or rust. The AISI number behind 18/8 is not given, where one listing in this group names 304 | Up to 12 hours — stated. It is the common figure on this shelf: several of the twelve listings here claim 12 hours or less, and one claims 18 |
| EcoVessel 8 oz with shot cup | $10 | 8 oz — stated, about 240 ml, with a separate 3 oz silicone cup that fits into the base. It is the smallest capacity on this shelf by a wide margin, where the rest run from 16 to 40 oz and the European side reaches a liter | TriMax triple insulation — stated by name. It is the only triple-wall claim on this shelf; every other listing here states a double wall, and this shelf's introduction opens on the assumption that the physics is shared. No layer materials are described | Not named. Food-grade stainless steel is stated, described as rugged, and no 18/8 or 304 figure appears | Not published separately. The listing states that drinks are kept at the perfect temperature for up to 24 hours, without saying whether that applies to hot, to cold, or to both — and this shelf's introduction notes that each figure comes from conditions the maker sets |
| Fanhaw 40 oz, three lids | $12 | 40 oz — stated, about 1.18 liters. The listing adds that 18, 24, 32, 40 and 64 oz versions exist, which confirms that capacity is a variant of one listing in this category rather than a separate product | Advanced vacuum insulation — stated, with no layer count. The word vacuum is used, which two listings on this shelf avoid | Not named. Food-grade stainless steel is stated, with resistance to rust, dents and odors, and no 18/8 or 304 figure. It is the only American listing in this group not to state 18/8 | 12 hours — stated. The common figure on this shelf |
A day bag where 500 ml of double-walled stainless steel is the whole requirement and the hours are not being compared.
Amazon reports what buyers took in the month before this page was last checked: at least 50.
The figure is a floor, rounded by Amazon, and read through Keepa — it says what buyers picked, not what a maker claims.
Specifications: the manufacturer sheet for camping and hiking gear and the matching Amazon product page. Prices and availability: Keepa. Every figure on this page names its source.
1 liter · 18/08 stainless · 13 h temperature stability stated, hot and cold not separated · bottle brush, jute bag and carabiner supplied
A 1 liter flask supplied with a natural-bristle brush and a carabiner, whose single retention figure of 13 hours is never split into hot and cold.
Best for: A liter bottle bought with its brush and its carry loop, where cleaning matters more than a comparable hours figure.
≈ $33
500 ml · vacuum insulated · SUS 201 outside and SUS 304 inside · 24 h cold and 12 h hot stated · brushed finish · top handle
The only flask here that names a different steel for the inside and the outside, alongside a stated vacuum, both retention figures and a brushed finish.
Best for: A day out where a named inner steel, a stated vacuum and a dishwasher-safe body matter more than the hours quoted.
8 oz · TriMax triple insulation, the only triple-wall claim here · food-grade stainless, grade not named · 24 h stated once, hot and cold not separated · removable 3 oz silicone cup · folding hidden handle · dishwasher safe, flask and cup
The only triple-wall claim on this shelf, on an eight-ounce flask with a removable three-ounce silicone cup in its base — and a single 24-hour figure that does not separate hot from cold.
Best for: A hip-pocket flask for spirits or a single coffee, where two can share from one cup
≈ $10
