Need to know: Not dishwasher safe, button-operated lid, comes with one cup, also available in 350ml and 500ml sizes

You may think choosing a vacuum flask is a simple matter of grabbing the shiniest example in the camping shop (if it’s open!) and hoping for the best. Well, unfortunately we’ve tried that approach several times and have frequently been disappointed. We examined each flask and its pouring mechanism and attachments for faults. We penalised flasks that had faults affecting their usability. Available in a range of colours (we like the electric blue), the flask is highly suitable for camping trips and general travelling refreshments. Pouring is very easy due to the superb flexible handle fabricated from silicone. 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.Avoid abrasive detergents and materials when cleaning your flask – bleach will stain and damage stainless steel, and scouring pads will scratch the outside of your flask The Milu Thermo Food Flask is a bowl-shape flask (16 x 10 cm) that is not only useful for keeping your drinks hot/cold, but also certain types of liquid-based food. You can keep soup, rice, noodles, fruits and even baby food in this great flask. All parents know that it’s often a problem carrying baby food at the right temperature. The 450ml flask Milu is a great solution to the problem.

This flask from OKADI gets full marks for its capacity and versatility. OKADI is a brand that has been serving people with quality products for the last 20 years and this particular model is their flagship model. It’s a big flask for big groups As we said before, the Milu is more bowl-shaped and can easily be eaten from directly. The 6.6cm wide opening is extremely convenient for easy filling and eating as well. You can leave your house with a full bottle of coffee on Friday evening and can have a nice walk with a cup of hot coffee on your weekend destination even on Saturday evening! You will definitely get a duration of 24 hours, and this model performs equally well for hot and cold temperature contents. In UseA range of scientific research has shown that BPA can seep into food or beverages and potentially cause a range of issues for the brains of fetuses, infants and children. Additional research suggests a possible link between BPA and increased blood pressure. The 18-8 flask is from the renowned brand Stanley. Stanley has been serving people since 1913 and this model is truly legendary. No other brand apart from Thermos themselves can boast such heritage. Dimensions

The GSI MicroLite 1000 Twist Water Bottle is a vacuum insulated stainless steel flask that has a one litre capacity but impressively small size and density. It is extremely lightweight at 0.37kg which is less than half the weight of the Stanley 18-8 for the same capacity. Glass-lined flasks are more dangerous because glass walls can also shatter To be safe, it's best to empty the contents after 24 hours.Thermos flasks use an ingenious mechanism which consists of dual layers separated by a vacuum cavity between them. The vacuum is a region of space with no air or anything at all in it – this creates a natural barrier to heat leaving or entering the innermost chamber holding your drink. That’s why liquids in the flask remain hot or cold for longer than they would in a standard plastic bottle. 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.