Wire ball holders are designed to conceal a manipulation ball or egg (or similar device) and are usually cliped near the edge of a coat, such that they can be easily accessed when needed and the item can be removed quickly. They serve a very basic execution but serve it consistently well.
These are ususally used in billiard ball routines, allowing the performer to “steal” extra balls, for production or color changes. A hollow ball is also a great thing to store them in so you can transform a silk into a ball. This unit can hold different sized balls but primarily are best set for a particular size and not attempted to change the sizing later, especially to a smaller ball. They are sturdy and will last, but they are a utility item, and as such the more you use them the sooner you will be needing a replacement.
Note: Ball Holder does NOT come with ball. Photo used for is for “conceptual” purposes only.