Big Horn 19275 Sliding T-Bevel (Adjustable) 10-1/2 Inch. Consumer friendly, easy to use adjustable sliding T-Bevel, much better than others of similar design which are made of light guage aluminium causing stiff hands while using. The locking screw is located at the bottom of the handle, so it never gets in the way of your work.  

These highly accurate, self-centering hinge drilling hinge bits are used for precise drilling of holes for cabinet and door hinges, door butts, striker plates, window pulls and all large and small hardware. Desired depth is achieved by loosening a setscrew, setting the high speed drill bit, and then tightening the setscrew. Bit is Self-centering & accurate. Body has screw top for ease of cleaning & changing bit. Replaceable bits. Bodies are stamped with size. The spring loaded outer guide keeps drill centered for perfect pilot holes. Top unscrews for easy cleaning.