Martin GF-1 type timing pulley, suitable for use with 3/4" and 1" wide Heavy (H) pitch profile trapezoidal tooth belts in power transmission applications that require synchronous rotation. Double flanges on the pulley resist side thrust and maintain belt contact. Model 36H100SK TXJ: 1/2" pitch; bore range of 1/2" to 2-5/8"; max RPM 4410; mounts to a drive shaft using an SK type quick disconnect bushing (sold separately). ASTM A48 Class 30 gray cast iron construction resists wear, galling, and corrosion. Unused (new old stock) , in original box.