Strap: 10mm thick with strap Small: Dimensions: 9.8" x 3.75". Size: Mens 7-8, Ladies 6-8 Medium: Dimensions: 10.5" x 4.25". Size: Mens 8-10, Ladies 9-10 Large: Dimensions: 11.5" X 4.375”. Size: Men 10-12, Ladies 11+