Check the listing for details. NEMA23 Planetary Gearbox Gear Head 3000rpm Speed Reducer 1/4" 6.35mm 8mm shaft. Condition: New. Listed at 33.90 USD. Description Product: Planetary Gearbox Reducer for Nema23 Stepper Motor / Flange=57mm; Adapter motors: Fit for 6.35mm( 1/4" ) or 8mm Shaft Nema 23 Stepper Motor; Gear Ratio: 4:1 5:1 10:1 20:1 25:1 40:1 50:1 100:1 input Shaft:6.35mm( 1/4" ) or 8mm,（If your device requires an input hole of 6.35mm, installing a shaft sleeve will reduce the 8mm to 6.35mm） Output Shaft: 14mm Rated output torque:29Nm Body length: 66mm Full load efficiency ≥ 95% Max radial force: 320N Max axial force : 240N Max input speed: 4000rpm Rated input speed: 3000rpm Backlash Precision ≤ 20 Arcmin Applications: This planetary gearbox is mainly used to reduce speed and increase holding torque, widely applied in CNC machine, such as engraving machine, milling machine, lathe, work bench, grinding machine .