To maximize performance, Pinewood Derby cars should be weighted to the maximum weight allowed. PineCar #P350 Round Weights are easy to use - just drill a 3/8" hole in your car and insert weights. They can be cut with a razor saw or hacksaw to fine tune your car's weight. Package contains 3 weights of approximately 1 ounce (38.3 grams) each. Choking hazard - not for children 3 or younger.