Our tungsten rods are a great non-toxic, high-density weights that are perfect for tuning your derby car weight and center of gravity. Drill a 3/8" hole and place the weights to keep them in place. Finish your car's tuning with some of our tungsten putty on race day with the official scales to hit just the right weight and find the perfect balance for the fastest possible car. Tungsten is similar to lead, but non-toxic and 1.7 times more dense. And, it's 2.7 times more dense than zinc, which some sell as a non-toxic alternative to lead! That means that you can hide the tungsten wherever you want and keep your car looking great. Each resealable package comes with 3 ounces of tungsten rods, 4 - 0.5 oz. pieces and 4 - 0.25 oz. pieces. They are sized at 3/8" in diameter so that you can easily drill a hole to conceal them inside your car.