Jacoby pool cue extension. This extension comes with the screw-in adapter butt bumper. Once the bumper is installed the extension can easily screw on and off during play. The Jacoby Extention has a unique feature that improves longevity. The joint and butt cap of this extension is made of a light grey phenolic material (much like the Phenolic tip on a break cue) that adds more protection against scratches and chipping.