Outer diameter: 18 cm; inner diameter: 15 cm; Adjustable swimming hat for babies and adults over 6 months. Waterproof effect: All parts of the head circumference are made of silica gel, elastic, soft and comfortable, and waterproof effect is super. Multi-purpose: Ideal for baby shampoo, shading and haircut. It can protect the child's eyes and ears from water during bathing or haircut. A fun experience for the kids, very useful and practical. Safe shampoo shower cap for babies, kids and children to keep water and shampoo away from eyes and face, also good protection for your baby from sunscreen and haircut. All head circumference parts are made of silica gel, elastic, soft and comfortable, and waterproof effect is super Outer diameter: 18cm; inner diameter: 15 cm; Adjustable bath hat for 6 months or more babies and adults. Multipurpose: Ideal for baby shampoo, shade and haircut, it can protect the child's eyes and ears from water during bathing or haircut, makes a fun experience for the baby Children, very useful and convenient.