Officially licensed by the Boy Scouts of America. Gain a competitive edge and make your Pinewood Derby racer run faster. Just add Round Chassis Weights! These ultra-safe, 99.99% lead-free weights are sectioned off into different sizes, allowing you to easily fine-tune your car per race regulations. Install by drilling a 0.4 inch dia. hole into your racer, and then use glue (sold separately) to safely secure the weights to your car's chassis. Pliers and glue required.