... current output 4.5A(SR4) / 7.8A(SR8) 2.Power supply 24-28V (SR4)/24-75V(SR8) 3.Microstep 2-256 available 4.small size ... , 5000, 8000, 10000, 20000, 25000 step/rotate5. speed range with appropriate stepper motor ,the speed can reach to 3000rpm6. resonance-restain can ... idle current 25%,50%,75% or90%9.Self-checking, motor with 1 turn/s speed do two laps positive & negative reciprocating ...