This is high torque 17 stepper motor with 1.8 deg. (200 steps/revolution). Each phase draws 2A, allowing for a holding torque of 45Ncm(63.7oz.in). This stepper motor is for the RepRap , Mendel 90, Rostock and similar 3D printers, as well as CNC and robotics applications. The motors are supplied with a long power cable with a 4-pin female connector already fitted - ready to ! Electrical Specification: - Manufacturer Part Number: 17HS16-2004S - Motor Type: Bipolar Stepper - : 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 - Length: 21mm - Number of Leads: 4 - Lead Length: 1000mm - Weight: 310g Connection: Black(A+), Green(A-), Red(B+), Blue(B-) Warning: Make sure the to a constant current or chopper drive controller before motor. Connecting the motor directly to a power supply will destroy the motor. Package list: 1 * Stepper Motor 17 Bipolar 40mm 64oz.in(45Ncm) 2A 4 Lead 3D Printer Hobby CNC