Machined steel block allows you to mate the hammer and sear (or trigger) outside of the firearm for a clear, unobstructed view of the critical point of engagement. Accepts a wide selection of hammer and sear pins sized for various handguns and rifles. Dovetailed adjustment block rides in slotted channel so pin spacing can be precisely set to match individual frames and receivers. Allen screw locks the pin setting so hammer and sear can be dropped in place relative to their actual position in the firearm. Great for cutting the engagement surfaces on new parts or fine-tuning the factory ones. Pins are individually numbered for proper identification.