Wheeler's 100-Piece Professional Gunsmithing FAT Wrench Screwdriver set is the kit that belongs on every gunsmithing bench. The well though-out bit selection will put an end to burred, buggered, and busted up screws on any gun that comes your way. The bits make up the heart of any screwdriver set, and Wheeler's are the finest available. They bits are made from S2 tool steel and hardened to 56-58 Rockwell "C". Unlike other screwdriver suppliers, Wheeler's engineers measured the screws on over one hundred modern and antique firearms to make sure that we offered bits for every situation. To top it off, this kit includes the FAT (Firearms Accurizing Torque) Wrench, which is used to apply precise inch-lb. pressure on all of your screws.