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 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 in the shell! Otherwise, there may be a buzzing alarm! The product is suitable for 2106/161/169 brushless electric wrenches. 18V 21V Brushless Angle Grinder Drive Plate Polishing For Machine Brushless sensorless angle grinder drive control board general Control board drive voltage: 18V (5 strings of lithium batteries, fully 21V), power 300W. Colour:Black Material:plastic Package Contents: 1 x Control board With Switch Only the above package content, other products are not included.