The product is compatible with 2106/161/169 brushless electric wrenches and has been tested before sale. 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 or TV, which are actually 18V systems (5 series 2 parallel 10 cells or 5 series 3 parallel 15 lithium batteries, fully charged to 21V) Before testing the machine, connect the wire, secure the motor, install the housing, tighten the screws, ensure the square shaft rotates freely without obstruction, connect the power supply, and press down the speed control switch so there is no gap in the shell. Failure to do so may result in a buzzing alarm. To prevent damage to the control board, please follow all instructions carefully. Color: As shown Material: Plastic + Metal Type: A Package Contents: 1 x Control Board 1 x Switch Note: The package includes only the items listed above. Other products are not included. Lighting and display differences may cause slight variations in color between the image and the actual item. Measurement error allowance is +/- 1-3cm.