Features: Drive integrated overvoltage and overcurrent protection Input signal optical isolation. Bipolar constant current chopping mode Direct Current power supply 20-50VDC, large drive current 4.2 A Output current dial switch adjustable. Low speed zero vibration, and low noise High subdivision: 2,4,8,16,32,64,128,5,10,20,25,40,50,100,125 Specification: Storage temperature: -20-65 degrees Celsius Humidity: 40%-90% RH Vibration: 10-50HZ/0.15mm Maximum operating current: 4.2 A Maximum top current: 5A Maximum breakdown: 128 Size: 118x87x33mm Package Includes: 1x Stepper 1x box 1x manual Package List: 1x Stepper 1x box 1x manual