Distribute weight to the best center of gravity (CoG) location and optimize your car's performance and stability. 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 23/64" (9.12 mm) drill bit. The CoG System is designed to fine-tune a car’s center of gravity (1/2" to 1" forward of rear axle) (6.35 mm to 2.54 cm) and is not intended to overcome extreme weight distribution.