This is the famous Kahler 8 string locking nut. It has a width of 2 1/4" (57.5mm) with a 15" radius. The string director is mounted on the base just behind the clamping plates thus eliminating the need for a string bar or string trees. Rounded string bumpers help guide the strings through the clamp plates and on toward the tuners without snagging which greatly reduces the risk of string breakage between the locking point and tuner. The string director also prevents the string from rubbing on the locking screw under the pad.