Joint protectors are made to serve 2 main purposes: to reduce the risk of bending joint pin, and to protect the joint collars from damage due to an impact. Joint protectors are an inexpensive way to help preserve your cue investment. These joint protectors are made from Cerocite, a high-impact plastic. Common cue brands featuring the 5/16 x 18 joint style are Meucci, Sterling, Action, Stealth, Viking, and Mali.