Neoprene cover to keep liquids cold. Handles are easy for baby to grasp. Fits 8 oz. Baby Bottle, Stainless Steel Bottle, Water Bottle and Aqua Bottle. The Green Sprouts Bottle Sleeve can covert most bottles into a two-handled, tot-friendly drinking apparatus. Made of neoprene, the sleeve helps keep beverages cool and protects bottles while providing two nice grips. Though the sleeve is made to fit Green Sprouts products such as the 8-ounce baby bottle and 12-ounce stainless steel bottle, it also fits other bottles.