This is the driver board, powered by a single-cell lithium power battery. The driver has memory function, battery low voltage protection, anti-reverse connection protection, and temperature control protection. Input voltage: 3-4.2V. Output: 3V constant current 5A. Gear settings: four levels of micro-brightness - low brightness - medium brightness - high brightness, double-click to explode. When the memory is turned off, the gear is automatically set and the temperature control is automatically set (reduce the current when working at 50 degrees, The current slowly picks up at 45 degrees) Gear current ratio: 10ma-500ma-1500ma-5A Diameter size: 17 mm. With reverse connection protection and low voltage prompt, the LED positive and negative wires and springs are welded. Color: As Shown Material: PCB Package Contents: 1 * Circuit Board Only the above package content, other products are not included. Note: Light reflection 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.