This is high torque Nema 17 stepper motor with 1.8 deg. step angle (200 steps/revolution). Each phase draws 2A, allowing for a holding torque of 45Ncm(63.7oz.in). This stepper motor is for the RepRap Prusa, Mendel 90, Rostock and similar 3D printers, as well as CNC and robotics applications. The motors are supplied with a 1 metre long power cable with a 4-pin Harwin female connector already fitted - ready to plug and print Electrical Specification: - Manufacturer Part Number: 17HS16-2004S - Motor Type: Bipolar Stepper - Step Angle: 1.8 deg. - Holding Torque: 45Ncm(63.7oz.in) - Rated Current/phase: 2A - Phase Resistance: 1.1ohms - Inductance: 2.6mH+/-20%(1KHz) Physical Specification: - Frame Size: 42 x 42mm - Body Length: 40mm - Shaft Diameter: 5mm - Shaft Length: 23mm - D-cut Length: 21mm - Number of Leads: 4 - Lead Length: 1000mm - Weight: 310g Connection: Black(A+), Green(A-), Red(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.