To maximize performance, Pinewood Derby cars should be weighted to the maximum weight allowed. PineCar #P3915 Tungsten Putty makes it easy to make last minute modifications to your racer's weight distribution. Tungsten has 3 times the density of traditional weights so a little putty can make a huge difference! Package contains 1 ounce (28.3 grams) of Tungsten Putty. Choking hazard - not for children 3 or younger.