#4-5 (1/8" Diameter, 0.251 - 0.312 Grip)304 Stainless Steel Rivet And MandrelRecommended Drill Size: #30 (.1285)Package Of 100 Blind RivetsPerfect For Corrosive EnvironmentsBlind rivets are tubular designed with a mandrel through the center. The rivet assembly is inserted into a hole drilled through the parts to be joined and a specially designed tool is used to draw the mandrel into the rivet. This expands the blind end of the rivet and then the mandrel snaps off. Unlike solid rivets, blind rivets can be inserted and fully installed in a joint from only one side of a part or structure, "blind" to the opposite side.