Callahan consulted with several gunsmiths and hobbyists to create a comprehensive screwdriver set perfect for your next project. The Callahan 123-Piece Gunsmith Screwdriver Set includes just about every bit you could ever need, as well as 13 gunsmith bits designed specifically to help with the disassembly/reassembly of common firearms. And, because some bits are used more than others, several bits are provided in duplicate.