Istore ultra-soft, elasticity is good. no need to close your eyes when washing hair. make the shampoo a funny experience for the kids. when washing, it can prevent the clogging breathing. comfortable and flexible for time-and-time again use. to prevent the shampoo & water touches the baby's face. protects your baby or toddler's eyes from shampoo and water. when wash your baby's hair, water will not run to the baby's face. kids can use when the head perimeter is more than 40 cm (high elasticity) material: eva foam external max diameter: 28.5 cm. internal max diameter: 13.5 cm.