Professional grade threaded spikes provide easy spike customization and extend life of product. Traction: 36 easily replaceable threaded steel spikes per pair placed under toe, heel and ball of foot. Combination of aggressive rubber lug & steel spike pattern provides traction on any surface. Easy On/Off: Quick release buckle & strap system get you in and out quickly. Secure Fit: Molded rubber walls at toe, heel, and side provide secure fit. Includes: 10 additional replacement spikes & 1 replacement buckle Interior Dimensions: * Medium: 11.25 X 4 Inches. * Large: 12.75 X 4.25 Inches. * X-Large: 13.5 X 4.5 Inches. * XX-Large 14.25 X 4.75 Inches.