The Universal Hammer Spur Extension by Carlson's is an easy way to increase the ease of use for nearly every firearm with a hammer. The extension is ambidextrous and features knurled ends for a positive grip. Installation is quite simple: slide the extension over the hammer and tighten the set screw with the provided hex wrench. Overall length is 1.5" long, diameter is 0.375". Notes:Will fit all T.C. Contenders and most exposed hammer firearms: rifles, shotguns, handgunsThe hammer expander will require minor fitting to clear the frame at full cock on Henry, Marlin, Rossi, Winchester and other new models with cross bar safety