The stores in my area stock sewing machine belts that are apparently like giant O rings, round in cross section and made out of some kind of unreinforced black rubber. do not buy those if you want it to last more than a few months. That replacement became brittle and cracked around the short pulley on the motor side, due to the small radius.This belt looks to be fiber reinfoced and apprently a better polymer material. it is working great so far on my old singer clone sewing machine.