Distribute weight to the best center of gravity (CoG) location and optimize the performance of your car. Screw-in, adjustable tungsten CoG weights make it possible to distribute weight quickly and easily. Test your racer’s speed and fine-tune CoG weight placement with the included adjustment tool. Includes 3/8" drill bit. CoG system is designed to fine-tune a car’s center of gravity (1/2" to 1" forward of rear axle) and is not intended to overcome extreme weight distribution.