The product uses pulse width control frequency to achieve the speed of DC brushed motor. Note that when inputting power, the positive and negative power must be connected correctly, otherwise the speed regulator will burn out. "+" represents the positive pole, and "-" represents the negative pole. DC brushed motors are not divided into positive and negative, and the forward and reverse rotation of the motor can be achieved by switching two lines. Applicable matching motors: 550 775795 895 and DC brushed motors connected with two lines, DC reduction motors. Product Name:Brushed DC Motor Speed Controller Model:MSDC-B Power frequency:15KHz Working voltage & Current:DC12V-60 20A Output power:60-400 (20A) Colour:Black Material:Plastic Package Contents: 1 * DC Motor Speed Controller 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.