The temperature performance is excellent and compares favourably to the other top performers in the world of elite flasks. Your coffee will remain hot after 12 hours and your ice cubes will remain unmelted after a very decent 24 hours. So, you can still pour a chilled drink even after a long walk on a hot day. Part of this ability is due to the clever ‘honeycomb’ insulation used inside the Hydro Flask. It worked well for us!

If you take your thermos flask to the local coffee shop and ask them to fill it up instead of having your drink served in a disposable coffee cup with plastic lid then you will be reducing the amount of landfill and waste material which gets produced from these establishments. Win win in our books! Why ‘Thermos’? The flask has a BPA-free cup with enough space for several decent-sized cups of teas. The cup also helps ensure the flask remains leak proof. As we said before, vacuum insulation is important for keeping the heat energy inside your flask, and the Hydro Flask does this well. It is made of stainless steel that is extremely good for heat retention. 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. Similarly, it kept hot food such as pasta piping hot over a period of 10 hours. The flask’s design also proved practical as well as stylish, with neat touches including a handy foldable spork, which stores in its lid, and a rubber carry handle. While the 530ml version is suitable for single portions, those of you looking to share may want to opt for the more roomy 800ml option.

The Stanley 18-8 flask is the best option for a solo user in our opinion. It is a great performer which looks superbly rugged for your next arctic exploration and goes about its job efficiently, discreetly and expertly.

That being said, we found that performance was not quite as good as a dedicated drinks flask – the Milu will keep your hot drinks hot for six hours and the cold ones for 10 hours. You should carefully consider the required capacity of your flask before buying one. Have a think about how many people will require a drink from it, and who will be the person carrying it around. Is it for home use (some people take a flask to their home office in the garden), or carrying on a walk for rest and recuperation? The Oneisall measures 34.5 x 11.5 x 11.5 cm and weighs 1.2kg. For a large capacity flask, those are not actually bad specifications. And it really does look the business! Beautiful lines as they say!Capacity: Bigger capacity means more contents to enjoy. It also means more weight to carry, but only if you fill it to the brim. For best insulation, buy a flask that’s slightly bigger (but not heavier) than you need, and leave a couple of centimetres of air at the top. We’ve included capacity and weight info for all our flasks below.