Blue Logo slide sandals by BOSS. The slide sandals have a rubber upper. They have a cushioned insole and a non-slip sole. – Upper: Other Materials– Lining: Other Materials– Sole: Other Materials.– Please note that when you purchase shoes for your child, you should select a size that is 1.5 cm larger than your child's foot. Wellies and boots should be up to 2 cm larger, for extra socks and insoles.