This standard toy consists of a series of nickel-plated steel rings connected by a leather strap. The largest metal ring goes over the balls and cock, while the cock alone goes into the other rings.
Shown in picture is the 5 ring version: the first ring is 1.75" in diameter. Then there are two 1.5" rings, followed by two 1.25" rings. The entire length is about 3".
The 7-ring version: the first ring is 2" in diameter. The second and third rings are 1.75", the next three are 1.5", and the last one is 1.25". Entire length is about 4".