Quantitatively show the principles related to Hooke's Law with this complete apparatus. Includes a 14" metal rod that mounts on a 4-1/2" diameter base. Scale in centimeters and inches can be easily adjusted along the rod. The plated steel weight holder and spring are attached to an adjustable collar with crossbar. Requires slotted weights (not included - we recommend UNWHST08 set of 8 slotted weights). Includes activity guide.