This motor is equivalent to 17HS8401 Model No. Step Angle Motor Length Rated  Current Resistance /Phase Inductance /Phase Holding Torque Inertia Of Rotor   Lead  ( °) (L)mm (A) (Ω) (mH) (Ncm)  (gcm²) (No.) 42HD6021 1.8 481.52.24.4 5082 4