This Gear Review first appeared in the MAY 2023 issue of Trucking Magazine. Click here to buy BACK ISSUES online

There can be no doubting what keeps the country running is Tea – or maybe coffee if that’s how you get your caffeine hit. Whichever it is, some form of hot beverage is probably a central feature in almost every cab at some time during the day.

Isn’t it also the first thing we look for when perusing a new truck? The cup-holders!

But how do you maintain a steady supply throughout the day? Sure, you can top up at a truck-stop but for a long hike there’s nothing better than your own stash, namely a flask.

So we thought we’d take a look at the options

The good thing about insulated flasks is that they can keep liquids cool as well as hot, it is one of the selling points that manufacturers mention: How many hours it can keep things warm or cold. But do their claims stand up to scrutiny?

We took six of the most popular flasks, each with different characteristics, filled each to the brim with boiling water then measured the temperature again after 5 hours. The results were surprising. One still maintained the temperature at a remarkably high 84°C while the ‘worst’ had cooled to just 48°C, still just about warm enough to enjoy, but not quite enough to be considered a ‘hot’ drink.

Klean Kanteen TK Wide

Capacity: 592ml

Temperature after 5 hours: 70°


The Klean Kanteen is a 20oz flask (592ml) with a slim design that would sit happily in most cup holders, the diameter is just under 3” (75mm) but being a larger capacity it is rather tall at 10” (250mm) so I wouldn’t want to fill it with hot coffee in a shallow dash-mounted cup holder.

However, it really is a very neat design with a folding handle built into the lid and a nice tactile finish to the outer body.

It is very secure when closed and just a twist of the spout opens it enough drink safely with little chance of spillage.


Capacity: 350ml

Temperature after 5 hours: 48°


I have to confess that I have used Bodum insulated mugs like this for over ten years and always been happy with their performance. They are available with different lids including a cafetière-style ‘plunger’ which allows you to make fresh coffee in the flask itself.

The fact that it was the worst performer in terms of heat retention was a surprise. I’d always been happy that I could make coffee before leaving the house at 6am and just sip it pretty well all morning until lunchtime.

It is smaller than some of the others with a volume of 350ml but it does mean it safely fits more cup holders too, with a base slightly narrower than the Klean Kanteen, 65mm diameter.


Capacity: 300ml

Temperature after 5 hours: 60°


This handy little flask from LifeVenture is the most compact of the bunch tested here. With a capacity of just 300ml it gives you a drink about the same as a mug of tea. But with a diminutive size of just 65mm diameter and height of 170mm it is almost small enough to keep in a jacket pocket.

Very easy to use with one hand, just flip the lid to access the spout. Heat-wise it did better than the Bodum but not as good as the SHO, but its compact nature and easy of use makes this one to consider if you tend to drink your coffee or tea quickly.

SHO Flask

Capacity: 750ml

Temperature after 5 hours: 84°


This one was a real surprise, although it does have a vacuum insulated body it is actually sold as a cold water drinking container rather than a hot water flask. Removing the top after 5 hours and instantly seeing the steam rise from the opening was not expected.

It performed the best on test, retaining hot water at 84°C after 5 hours.

The only downside is that it is a narrow screw top. A feature which obviously helped it retain heat but it does make it fiddly to open, not really something you could open and drink from with one hand while driving.

The narrow spout – 30mm wide – also makes it harder to fill with hot water from a kettle. It has a slightly wider 75mm diameter body and stands a full 12” (300mm) high.

Large Thermos

Capacity: 1000ml

Temperature after 5 hours: 80°

(Nearest Equivalent: £25)

OK, so I pulled this one out of the garage, simply to provide a baseline of what a good, old-fashioned Thermos Flask can do. It has served us well for over a decade and shows no signs giving up yet.

It is quite a monster to lug about but it does hold one litre of liquid, and as the test results show, it managed to keep it pretty hot at 80°C after 5 hours, only narrowly losing to the lower capacity SHO flask.

Thermos sells a gazillion different varieties of flask so they’re sure to have one that suits you.

Thermos Stainless King Food Flask

Capacity: 470ml

Temperature after 5 hours: 70°


This isn’t really suitable for just keeping water, coffee or tea hot, it is sold as a food flask so is perfect for soup, chilli or even just pasta. It maintained a heat of 70°C after 5 hours which would mean you’re still going to have to blow on your grub before eating it.

The folding spoon included in the lid is OK but I found it folded up while I was trying to use it a couple of times.

Having said that it’s perfect for heating something up at breakfast time and keeping it hot until lunch.

I tried a couple of the flasks with various Pot Snacks. Most of the standard sized snack pots need 250-300ml of water to transform the dehydrated stuff into a palatable lunch so the smaller 300-400ml flasks will only do you one Pot Noodle and a very small coffee.

The Klean Kanteen will make two, the larger SHO flask will make three and the monster Thermos will make four pot snacks. Although if you are eating four pot noodles in a single day we maybe need to discuss your diet!

This Gear Review first appeared in the MAY 2023 issue of Trucking Magazine. Click here to buy BACK ISSUES online