Professional grade threaded regular 3mm spikes provide easy spike customization and extend life of product. Quick release buckle and strap system for easy on, off. It has 36 easily replaceable threaded steel spikes per pair placed under toe, heel and ball of foot. Molded rubber walls at toe, heel, and side provide secure fit. Combination of aggressive rubber lug and steel pattern provides traction on any surface. Includes 10 additional replacement spikes and 1 buckle. Single unit dimensions 16x7x4''. Sizes: M(7.5-9.5), L(10-11.5), XL(12-13), XXL(14-15). Material: Rubber, Steel.