Our recommendations below have managed to master the art and science of the vacuum flask – that ingenious, insulated container that does the job of a portable kettle or fridge without the need for a plug socket. Made from multiple layers of BPA-free and rust-proof stainless steel, these flasks should survive years of bumps and knocks, keeping you in hot cuppas and ice-cold drinks season after season. The leakproof café cap and the twist valve seal on its lid are so effective that you also have an insulated water bottle, soup carry-cup and a handy little ice caddy for filling with ice cubes, all wrapped up in one package. We liked the push button on the lid – push it in to drink from it, push it again to lock it and seal in heat. A solid performer in testing, SHO’s food flask kept water chilled for the advertised 20 hours and even managed to keep a portion of ice cream very cold, albeit a little melted, for the same period of time.

Out of sheer curiosity, we also filled it with ice over a weekend and discovered minimal melt at the end of it.Once sealed, it can keep food hot for up to six hours, while boiling water will stay piping for ten or more.

Key specs – Material: 18/8 stainless steel with copper coating (dishwasher-safe); Capacity: 1l; Size: 23 x 12 x 11. The size you pick should be based on your individual needs, as well as the activities you might be doing while using it. Key specs – Material: Stainless steel (not officially dishwasher-safe); Capacity: 470ml; Size: 22 x 6. A Thermos King will last years but it’s not officially dishwasher-safe, and you’re not even meant to submerge it in water (if you do, you kill the manufacturer’s 50-year guarantee).Key specs – Material: 18/8 stainless steel (not officially dishwasher-safe); Capacity: 470ml; Size: 14. And if you’re heading out there with a friend, even better, because there’s a second plastic ‘buddy cup’ hidden inside the larger metal one.

The two-part locking lid doubles as a rotatable spout, so it’s ideal for taking a sip when you’re walking, although the plastic part of the lid does feel somewhat less durable than the metal. uk/browse/sports-and-leisure/camping-and-caravanning/flasks/c:30512/type:pump-pots/" on this server. The specifications state that hot drinks will stay steamy up to eight hours, whilst cold ones will be cool for 12. However, the efficiency of this insulated flask and its brushed stainless steel styling makes it one of our favourites.We tested flasks that could hold enough for several people (or someone wanting several cups during the day), as well as some that were designed to serve one. On some flasks, you need to unscrew the top before pouring, while others open by pushing a button (or similar).