Thermos is probably most commonly associated with their range of flasks but they also produce other items, amongst them this Hydro Active sports bottle. This was bought several months ago for my eight year old son, mainly as he likes to take a drink of water to bed with him and this seemed like a suitable option to keep his drink fresh through the night.

This particular sports bottle has quite an innovative addition, designed to keep drinks cooler for longer. The bottle actually comes with a removable plastic core which needs to be filled with water and placed in the freezer for an hour or so. Once frozen, the core simply rests securely inside the bottle and acts like a jumbo ice cube, helping to keep the drink cold for longer. Whilst this might sound like a bit of a gimmick, it does actually work surprisingly well although it is, obviously, much more effective if the liquid in the bottle itself is icy cold before adding the frozen core otherwise the drink will cause the ice to melt too quickly. When using a cold drink, this core can help to keep the drink cold and fresh for several hours so is ideal, not only for bedtime, but as a bottle for either sports use or for out and about during warmer weather. (Come on now, let's be positive!) If the cold core is still being frozen or not needed for any reason, the bottle can still be used as a standard sports bottle, so it is a fairly versatile and adaptable design.

The bottle is quite a nice size for all purposes, holding up to 450ml of liquid, according to the measurements (in both litres and ounces) indicated on the size. These measurements are actually only accurate without the core in place. Once the core is added it displaces some of the liquid so it seems a bit silly to bother with the measurements at all, to be honest - all the more so as they have started to wear off since being washed regularly in a dishwasher.

Aside from this slight fading, the bottle has proven to be a fairly robust design which has survived several months of regular use. It is made from sturdy, inflexible plastic but is easy to hold, despite its chunky appearance, as it curves in slightly at the sides and has rubberised grips so that it isn't at all slippery to hold. The lid opens easily and has a rubber seal so, providing the lid is pressed down fully, it is totally spill proof making it ideal for the gym or changing bag. It does take some effort to close it properly though and isn't always mastered immediately by certain children!

Once opened this is very comfortable to drink from. Rather than the traditional sports bottle spout, this one has an open rim (similar to the size and design of the drinking hole on a coke can, for example.) This kind of free-flowing opening is much kinder on the mouth and makes it quite refreshing to drink from.

I paid £4.50 for this bottle from Wilkinson, which I do think is relatively expensive for a drinking bottle. I think you pay a premium for both the Thermos branding and their reputation for quality products, as well as the addition of the innovative freezable core. Although this is expensive, I still think it is a bottle worth considering for either sports or personal use and would certainly recommend it.