The Slinky was invented and developed by American naval engineer Richard T. James in 1943. When the toys were first demonstrated at a local store, they were such a hit that the entire inventory of 400 units was sold out in under 90 minutes.
A slinky is a precompressed helical spring, which as well as being a classic toy, can also be used to demonstrate a number of science phenomenons such as the oscillation of waves.
There is some fascinating science, based on Hooke's law and gravity, behind the movement of a slinky, which is worth further investigation if you're interested.
These slinkies are approx 7.5 cm diameter and come in a range of colours.
