PT28316 - Collet Adaptor Only This is a timesaving accessory for our 827 Series edge finders. It allows quick installation and removal of the edge finder, eliminating the need for collet changes on Bridgeports and similar machines. The progressive steps are: 1/4", 5/16", 3/8", 1/2", 5/8", 3/4" and 1". Step depths vary from .100" to .200".