For refrigerators, lavation machines, pumps, stokers, woodworking machines, etc. Do it belts feature film Concave Sidewalls to apply the belted ammunition replete traction on the pulley block sides. Rubber Filled Cords forestall breakup of cores and rubber. Protective Fabric Jacket (made from peculiar compounded rubber buy in) concerning soundless working, oil colour and heat-resistance.No. 3L000 Series: 3/8" top out x 40 chamfer (For A Pulley) No. 4L000 Series: 1/2" top out x 40 chamfer (For A Pulley) No. 5L000 Series: 21/32" top out x 40 chamfer (For B Pulley)