Rubber Imported Rubber sole Shaft measures approximately Calf High from arch Boot opening measures approximately 11" around KID-FRIENDLY WATERPROOF BOOTS | The main material we use in our rain boots is natural rubber. Rubber is durable, flexible, and waterproof - perfect for everyday play! The handmade vulcanization process eliminates weak spots in our rubber. SOFT, COMFORTABLE LINING | Nobody wants to wear boots that are abrasive and rough – especially kids! We line our boots with faux fur lining that is soft and warm.