Pinewood Pro Derby Weights Tungsten Weights 3oz, Eight 3/8&rdquo; Incremental Cylinders to Optimize Car Weight to Make the Fastest Derby Car HIGH DENSITY, LESS SPACE - Tungsten is 1.7x denser and smaller than lead. It is 2.7 denser than zinc making it about 1/3 the size of zinc! This allows you to pack the most amount of weight in a small area to give more inertia producing more speed at the finish line EASILY TUNE FOR MAX SPEED - Multiple sizes make precise tuning of your Pinewood Derby car easier. HIDE WEIGHTS OR SHOW THEM OFF - Cover the weight holes with wood filler, sand smooth, and paint, keeping your speed secret safe. Alternatively have them stick out the back looking like real exhaust pipes EASY INSTALL - Cylinders are 3/8 diameter (standard drill bit size) With chamfered edges, these cylinders will slide easily into your drill holes SAFE - Tungsten is child-safe, non-toxic for safe handling. No sharp edges.