a yoyo is made of two uniform disks

A yoyo is typically made of two uniform disks, which are attached to each other with a central rod or axle. The disks are usually made of plastic or metal and are the same size and shape. The string of the yoyo is wound around the axle and the yoyo is thrown, causing the string to unwind and the yoyo to spin. When the yoyo reaches the end of the string, it can be pulled back up to the hand by winding the string back onto the axle.

The uniformity of the disks ensures that the yoyo spins smoothly and evenly. The central axle also helps to keep the yoyo stable as it spins. Some yoyos may have additional features, such as ball bearings or adjustable gaps, which can affect the yoyo's performance and make it easier or more challenging to perform certain tricks.