MXL Series Pitch: 2.032 mm Pulleys details: Tooth number 20, Tooth width 7mm, Bore 8mm, Flange: double. Timing Belt details: Tooth number 300, Belt Width 6 mm, Inside Length: 24" (609.6mm) Good anti-cracking performance, and small extending rate Package included: 2Pcs 8mm hole aluminium pulleys + B300MXL Timing Belt + 4Pcs grub screw + 1 wrench