pulley with 20 teeth or grooves is of the best choices for 3d printer structure , Compared with T2., 5 or MXL synchronous pulleys, the tooth profile of pulleys has anti-backlash function. uxcell GT-2 Synchronous Wheel 20&60 Teeth 6.35mm Bore, Aluminum Alloy Timing Pulley Gt2 Belt GT2timing-Belt Closed Loop 200mmpulley With 20 Teeth And 60 Teeth For 3D Printer Timing Pulley 2GT timing pulley; suitable for Re-prap, Pru-sa, Mendel-Max, 3D printers The arc tooth profile is small in pitch, suitable for linear drive; pulley with 20 teeth or grooves is one of the best choices for 3d printer structure Compared with T2.5 or MXL synchronous pulleys, the tooth profile of pulleys has anti-backlash function. See more product... The tooth profile is small in pitch, suitable for linear drive; GT2 pulley with 20 teeth or grooves is one of the best choices for 3d printer construction. Compared with the T2.5 or timing pulley, the GT2 pulley tooth profile is anti-backlash. Pitch Length: 200mm Made of high-quality materials, durable