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:greenMaterial:plasticPackage Contents:1 * Stepper Motor Driver Control Board1 * 6P cableOnly 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.