Sparta sandals barefoot are made from leather and they utilize a very unique lacing style. The lace is leather and loops through the toe post and around the ankle. There are no knots on your foot, the strap simply loops under and sits slight recessed, providing a super flat smooth sole for the huarache. The result is a very light-weight sole with great ground feel that makes Sparta sandals barefoot amazing comfortable. The sole has 4 mm flexible long-lasting rubber.