This self-centering doweling jig comes with SIX removable screw-in bushings for extra hole pattern. Extra sizes are 1/4", 5/16” and 3/8” (2 of each size.) This will permit you to drill two holes parallel to one another for double dowel applications. This is on a 3/4" center-to-center space. The jig does not have to be moved to do this and is more accurate and convenient than other types of jigs. Works with material up to 2" thick.