Features: The product is suitable for 60A brushless electric wrenches. 21V Brushless Grinder Driver Plate Polishing Machine General Control Panel Size 5.2x6.2CM/6.2cmx5.2cmx0.9cmBrushless sensorless grinder driver control board general. Control board driver voltage: 18V (5 strings of lithium batteries, full charged 21V), power 300W. The battery pack marked with 48V, 68V, 88V, 98V, 128VF or TV can be used, and its voltage is actually 18V. Before testing the machine, you must first connect wire---fix the motor---install the case---tighten the screw---make sure that square shafts of the head can be easily rotated without jamming---connect power supply--- Press down speeds control so that there is no gaps in the shells! Otherwise, there be buzzing alarm! To prevent damage to the motherboards, please follow the requirement. Specifications: Material:Aluminum Alloy Size:Approx.52.5x62.5x9.5mm/2.07x2.46x0.37in Color:Black Package Includes: 1xControl Board note: Please allow 1-2cm errors due to manual measurement,please make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.