The product is suitable for 2106/161/169 brushless electric wrenches. 18V 21V Brushless Angle Grinder Drive Plate Polishing Machine General Control Panel Size 5.3x6.3CM Brushless sensorless angle grinder drive control board general Control board drive voltage: 18V (5 strings of lithium batteries, fully 21V), power 300W. The battery pack marked with 48V, 68V, 88V, 98V, 128VF or TV can be used, and its voltage is actually 18V (5 series 2 parallel 10 cells or 5 series 3 parallel 15 lithium batteries, fully 21V) . Before testing the machine, you must first connect the wire---fix the motor---install the case---tighten the screw---make sure that the square shaft of the head can be easily rotated without jamming---connect the power supply--- down the speed control switch so that there is no space in the shell! Otherwise, there may be a buzzing alarm! To prevent damage to the motherboard, please follow the requirements. Colour:black Material:plastic+metal Package Contents: 4 x Control board 4 x Switch 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.