“These pads fit the Socatt Quick Lock Discs and have a 1/4" UNC Female thread once the included mandrel is removed. This perfectly fits several compact direct drive air sander/grinders. As the 2" and 3" pads have a different sized disc attachment thread, I have 2 air tools, one for the 2" pad and another for the 3" pad. The dice lock on very well and true.”