The product is suitable for 18V brushless electric wrenches. It has been tested before shipping. 18V 21V Brushless Angle Grinder Drive Plate Polishing Machine Control Panel Size 5.2x6.2CM Brushless sensorless angle grinder drive control board Control board drive voltage: 18V (5 strings of lithium batteries, fully charged 21V), power 300W Compatible with battery packs labeled as 48V, 68V, 88V, 98V, 128V; actual operating voltage is 18V (5 series 2 parallel 10 cells or 5 series 3 parallel 15 lithium batteries, fully charged 21V) Before testing the machine, connect the wires, secure the motor, install the housing, tighten all screws, ensure the square shaft rotates freely without obstruction, then connect the power supply. Press down the speed control switch securely to avoid gaps in the shell. Failure to do so may result in a buzzing sound or alarm. To prevent damage to the control board, follow all installation instructions carefully. Color: As shown Material: Plastic + Metal Type: A Package Contents: 1 x Control Board 1 x Switch Only the items listed are included; other accessories are not included. Note: Lighting and monitor differences may cause slight color variations between the image and actual item. Measurement error allowed is +/- 1-3cm.