This is a MUST have for replacing Rivnuts for water bottle hardware, inserts for chain guard hardware, and the computer brackets on the handlebars of the new Schwinn AC bikes! A Rivnut is an insert put into a predrilled hole on the bike, then compressed with the tool to seat or immobilize it, then it is used for attaching hardware ranging from waterbottle cages, chainguards and computer brackets. If the Rivnut is stripped or compromised it must be re-tapped, recompressed or replaced. This tool makes compression or replacement happen easily.This package includes assorted Rivnuts. The shaft on the RivGun is replaceable.