This is the strongest model for Nema 23 stepper motor, it with 1.8 deg. step angle (200 steps/revolution). Each phase draws 3A, allowing for a holding torque of 3.0Nm(425oz.in). Electrical Specification: * Manufacturer Part Number: 57HS56 * Motor Type: Bipolar Stepper * Step Angle: 1.8 deg. * Holding Torque: 3.0Nm(425oz.in) * Rated Current/phase: 3A * Phase Resistance:100mohm * Inductance: 6.5mH+/-20%(1KHz) Physical Specification: * Frame Size: 57 x 57mm * Body Length: 56mm * Shaft Diameter: 8mm * Shaft Length: 21mm * Number of Leads: 4 * Lead Length: 400mm * Weight: 0.7kg Connection: Red(A+), Green(A-), Yellow(B+), Blue(B-) Warning: Make sure the motor connect to a constant current or chopper drive controller before you test motor. Connecting the motor directly to a power supply will destroy the motor.