The MILWAUKEE M18 FUEL 1/4" Blind Rivet Tool w/ ONE-KEY Retention Nse Piece 4-Pack prevents inserted rivets from falling out of trivet tool when the tool is held in any orientation. 3/16", 7/32", 1/4" and 9/32" retention Nse pieces included. These rivet gun extension Nsepieces are laser-etched with the diameter size in English and metric units. Compatible with the 2660 M18 FUEL 1/4" Blind Rivet Tool w/ ONE-KEY (sold separately).