An economical set of 12 drilled balls for all your pendulum experiments. Set contains two each 25mm diameter balls of brass, aluminum, steel, wood, cork, and copper, in a plastic box for easy storage. All drilled balls feature 3mm countersunk holes so pendulum cord knots can be recessed.

WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer and reproductive harm. For more information go to http://www.P65Warnings.ca.gov