Splint Boots Protect Horses Legs This Gel Insert splint boot is light weight and offers the protection your horse needs to the cannon area. Don't let the weight of the splint boot fool you! The patented gel inserts will help cushion and absorb the blows to your horses legs. The gel insert is protected by leather grain PVC. Made of Neoprene with a nylon covering makes this splint boot completely washable.