Coiled Steel Spring with double loop ends. Overall Length End to end 50mm (1.96") , Spring collapsed length with out hoops 24mm (0.94") . Spring Outside Diameter 15mm (0.59"). Spring stretches to around 200 - 230mm to (Approx. 8 - 9 inches) and returning to normal length with no deformity. Perfect tool for studying motion of mass on a spring, Hooke's Law, potential energy, etc. It provides a visually and kinesthetically effective method for studying the physics of springs. Single Spring