Positive and reverse can be clicked; Press the forward button; Press and hold the forward button; Loosen the stop; Press the reverse button; Press and hold the reverse; Loosen the stop. Self-locking positive and negative; Press potentiometer forward; Press stop again; Press reverse again; Press stop again. Speed range: 0.1-999 rpm; power off memorable and last set speed value. Colour:green Material:plastic Package Contents: 1 * Stepper Motor Driver Control Board 1 * 6P cable Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.