Vario rings, also known as "spacer rings", are used to limit the speed of a scooter. These rings are placed in the scooter's transmission and limit the movement of the variator.

A variator is a mechanism that controls the speed of a scooter. It consists of two discs connected by a belt. When the engine is running, the variator will move the sheaves apart and tighten the belt, making the scooter go faster.

By placing a vario ring in the transmission, the movement of the variator is limited and the belt will loosen, limiting the speed of the scooter. This can be useful if you have a scooter that goes too fast and you want to limit it to a slower speed.

However, it is important to note that fitting vario rings may affect the scooter's warranty and may result in reduced performance and additional wear and tear on the engine and other components.