Protect Form: Energy-saving semi-automatic current lock function, built-in temperature protection and over current protection, voltage protection, preventing reverse. The semi-flow functionality: The semi-flow function is a step of 200ms, and the driver output current is automatically reduced to the rated output current of 50%, used to prevent motor heating. Installation: Around to have 20mm of space, can not be placed next to the other heating equipment, to avoid dust, oil mist, corrosive gases, and high humidity is too big and strong vibration. Application: Suitable for any small and medium automatic equipment with CNC controllers, such as X-Y-Z tables, labeling machines, engraving machines, and pick-place devices. Parameter: Input voltage: 9~42VDC; Output Current: 0.5A~4.0A; Segment Optional: 1/2/4/8/6/32 Segment; Suitable for Step Motor: 42/57/86mm Stepper Motor Please note that there is a slight color difference or discrepancy in kind, it does not affect the use, please do not mind, thank you! Material: plastic colour: Black Package Contents: 8 x Stepper Motor Drivers