This is a set of 3 gold-plated string retainers for guitar, cigar box guitar and more. These are used any time you want to pull the string height down before they cross the nut, to help with break angle and get better string tension. These are especially good if you are building cigar box guitars without angled headstocks, which often have troubles with string height and break angle.
This is a wider and flatter style of string retainer, of the style sometimes seen on Fender(tm) basses. Some builders prefer this lower-profile style. Grooves run under the round part into which the strings seat.
A set of three of these will handle 6 total strings (each retainer handles two strings, one on each side of the screw post). Mounting screws are included.