The product is suitable for 2106/161/169 brushless electric wrenches. It has been tested selling OK. 18V 21V Brushless Grinder Drive Plate Polishing Machine General Control Panel Size 5.2x6.2CM Brushless sensorless 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 voltage is actually 18V (5 series 2 parallel 10 cells or 5 series 3 parallel 15 lithium batteries, fully 21V) . testing the machine, you must first connect the wire---fix the motor---install the case---tighten the screw---make that the square shaft of the head can be easily rotated without jamming---connect the power supply--- Press 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 the requirements. Colour: Material:Plastic + Metal type: A Package Contents: 1 x Control board 1 x Switch Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.