Adjusts to fit women"s size 5 to Men"s size 15, Heel adjustment strap for a more secure fit * Heavy duty rubber strap wraps around the bottom of the shoe, Matches the shape of the shoe * 3 single weight stretch pockets per shoe are designed to hold integrated flexible weights * Nylon Mesh for high visibility, Soft bound edges for extra comfort and tight pocket design prevents any movement of the weight * Oversized arch securing strap, Top strap secures weight for sprinting