Rubber sole.ADORABLE DESIGN: High-visible in the Gray Outside .100% WATERPROOF:Our rain boots always keep kids' toes and feet dry during wet days without falling. The streamlined waterproof surface design keeps water out.COMFORTABLE & LIGHTWEIGHT: In order to bring much more fun to your kids that these rain boots are made from a soft, flexible PVC that let kids run, skip, and jump in puddles without feeling stiff and constrained.EASY-ON HANDLES: Our design helps ensure ease of use for your little kids. With the reinforced handle design young kids can easily slide their rain boots on and off, without trouble.EASY TO WASH: These boots were meant for many occasions like camping, muddy trail hikes, climbing, hiking, playing in streams. After a day of fun, just spray the mud off under the hose or faucet and they'll be ready for the next adventure.