Clue number one: Its made of a very lightweight, but durable wood. Formed into a shape ( the picture shows a section of it).
It is training equipment- not specifically for hand strength development though. You’re honing in on it, MG. *Clue number two: Figure out what type of lightweight wood it is, the name of that particular type of wood is also part of the name of this training item.
It is in the shape of a ring, it can be used in a gym, but it’s not what you’re thinking, as far as “gymnastics” is concerned. It is called a ring, but what “kind of ring” ? Go back to the clues I provided.