This is a short geared NEMA 17 Stepper motor, total length inlcuding shaft below 80mm, and with 6mm diameter shaft. It has an integrated planetary gearbox with a 5.18:1 gear ratio, the resolution reach 0.35°step angle. It's a good solution in applications that need low rotation speeds and/or lots of huge torque.Please note, this planetary gearbox is not high precision gearbox, the backlash we can promised is <;=1 degree.SpecificationManufacturer Part Number: 17HS13-0404S-PG5 Motor Type: Bipolar Stepper Step Angle(W/O Gearbox): 1.8° Holding Torque: 121.2Ncm Rated Current/phase: 0.4A Phase Resistance: 30ohms Voltage: 12V Inductance: 34mH±20%(1KHz) Gearbox Type: Planetary Gear Ratio(Exact Gear Ratio): 5 + 2/11 Efficiency: 90% Backlash at No-load: <;=1° Max.Permissible Torque: 2Nm(283oz-in) Moment Permissible Torque: 4Nm(566oz-in) Shaft Maximum Axial Load: 50N Shaft Maximum Radial Load: 100N