Wave Form Helix ,Slinky, coil diameter 7.5 cm length closed 10cm-EIS-PH0708A offers a thoughtfully designed, durable resource for hands-on learning. A scientist's version of the classic toy!. (With a higher spring constant) Can be used as a scientific instrument to measure a wave function and for demonstrating a variety of physics concepts Send it down a wicked set of stairs for an exciting display Measures 4" when closed and 3" in diameter Stretches up to 3 meters in length!. Wave Form Helix - A Scientist's Version of the Classic Toy* Can be used as a scientific instrument to measure a wave function (it actually has a higher spring constant than the classic toy) Great for demonstrating a variety of physics topics including potential and kinetic energy, Hooke's Law, energy of motion and more Unleash the helix down a wicked set of stairs for an exciting display Learn impressive tricks!. This wave form helix measures 4" in height when closed, and 3" in diameter. Measures up to 3 meters in length when fully stretched!.