Longruner A4988 Stepstick Stepper Motor Driver Module + Heat Sink for 3d Printer Reprap (Pack of 5 Pcs) A4988 driver board widely used in 3D printers and small CNC machines Simple step and direction control interface Thermal protection, over-current protection, ground fault protection Five different step resolutions: full-step, half-step, quarter-step, eighth-step, and sixteenth-step Adjustable current control lets you set the maximum current output with a potentiometer, which lets you use voltages above your stepper motor's rated voltage toachieve higher step rates