The MAM Thermal Bag is made of high quality material and the insulating layer inside keeps hot water hot or cold formula/breast milk cool for up to four hours. The bag is easy to use and very convenient when out and about or travelling. The thermal bag has a handy velcro leash or hook so it can be attached to changing bags and pushchairs. It holds one MAM bottle and fits all sizes except the Trainer and Hold Me bottle types. To clean, parents can wipe with a damp cloth after each use and remove any milk spills immediately.