150 Springs Total Compression and Extension Springs Range in Length from 15mm to 300mm Range in diameter from 4mm to 18mm Range in wire thickness from 16 s.w.g. to 32 s.w.g. The sturdy, variable sized, compression and extension springs provide the perfect tools for studying motion of mass on a spring, Hooke's Law, potential energy, etc. They provide a visually and kinesthetically effective method for studying the physics of springs.