The Avent Thermabag bottle holder from Avent uses a 3M Thinsulate lining to help keep water warm/cold or your baby's formula, breast milk or baby food cool for up to four hours. The Thermabag will carry 2 x 9oz bottles or other items from the Avent Via or cup range. It has a soft Neoprene outer which can be wiped clean with a damp cloth.