Delrin joint protectors provides protection for the cue in several ways. For the shafts they protect the collars from possible damage when the cue is not together. Many cues have collars with intricate one of a kind designs that can difficult and expensive to duplicate should they become chipped or damaged. This kind of damage hurts the value of any cue. For the butt they provide protection for the screw as well as the joint in general. Delrin joint protectors also protect against damaging moisture due to humidity that can attack the end grain of the wood. You don't get this kind of protection from wooden, or cheaply made, poorly fitting joint protectors.