About this item:
Comprehensive set of 12 balls for classroom demonstrations. Perfect for any STEM exploraions or experiments.

Contents: 
* 1 drilled aluminum ball, 25mm diameter 
* 1 drilled copper ball, 25mm diameter 
* 1 drilled steel ball, 25mm diameter 
* 1 drilled wood ball, 25mm diameter
* 2 drilled brass balls, 25mm diameter
* 2 solid steel balls (one plain and one with suspension lugs)
* 1 brass ball with hook, 38mm diameter
* 1 steel ball with hook, 38mm diameter
* 1 copper ball with hook, 38mm diameter 
* 1 cork ball, 38mm

All drilled balls feature 3mm countersunk holes so pendulum cord knots can be recessed. Packed in a plastic storage box.