To maximize performance, Pinewood Derby cars should be weighted to the maximum weight allowed. Tungsten weights have 3 times the density of traditional weights to give you finer control about weight distribution. PineCar #P3915 Tungsten Incremental Cylinder Weights are easy to use - just drill a 3/8" hole in your car and insert weights. The incremental weight design allows you to adjust weights in 1/16 of an ounce increments. Package contains weights totaling 3 ounces (85 grams). Choking hazard - not for children 3 or younger.