Martin timing pulleys are manufactured to extremely close specifications and are stocked in minimum plain bore, taper bushed, QD bushed styles depending on size and pitch. Synchronous sprockets are non-slip toothed drives that require no lubrication. These sprockets have a wide speed range, are very efficient and make less noise than chain drives. Teeth on the belts are molded to conform with and engage the teeth on a mating sprocket. Martin HTS® High Torque Belt Drive Sprocket, Solid Type DF-1, Minimum Plain/Reborable Bore, 0.75 to 1.938 in Bore Dia, 3.956 in Outside Dia, 4.01 in, 40 Grooves, 8 mm Pitch, 3-3/4 in Face Width, 4.344 in Flange Dia, 3-13/32 in Hub Dia, 3/4 in Hub Projection, 4-1/2 in Overall Length, Steel