6N137 High speed optical culture to ensure high speed to ensure high speed without losing steps - 42.57.86 Step within 3A 2/4-thases / 4-wire / 6-wire stepper motor - Automatic half decay - Excitation mode: Synchronization, Half Step, 1 / 8 Step, 1/16 Step - Current level is adjustable to meet your application needs - Large heat sink for good heat dissipation - Overheating and overcurrent protection to ensure optimal performance