GT2 Pulley 18 Tooth 6.35mm Bore for Shaft of Nema23 Stepper Motor
RobotDigg put 20 Teeth GT2 Pulley 5mm Bore, 8mm Bore n GT2 36 Teeth Pulley 5mm Bore, 8mm Bore in stock for quick response but as you know 6.35mm Shaft is the standard diameter of a NEMA23 Stepper Motor. So RobotDigg decide to bring 6.35mm Bore GT2 Pulley as stock item for makers.
Combination:
GT2 18 Tooth Pulley 6.35mm Bore for Motor Shaft w/ GT2 36T Pulley 5mm Bore for 5mm Smooth Rod or 8mm Bore Pulley for 8mm Smooth Rod.