This is a pack of 8 thin plywood retainer nuts, intended for use on 3-string cigar box guitars (and other homemade instruments) with recessed headstocks and zero frets. See the listing photos for an idea of how these are intended to be mounted. These nuts do not hold the strings down at all - the break angle off of the tuners have to do that - this nut just keeps the string in the correct position going over the zero fret, so it doesn't move around while playing. Note: if your strings don't have enough downward angle to stay in place, you can always install screws partway between the tuner shaft and the nut to run them under, to help hold them down.
We designed these parts for use on our own instruments that have recessed headstocks and zero frets. They are cut from arctic birch plywood that is just under 1/8" thick, are 1.5" wide and 9/16" tall. There are two holes for mounting and 3 string notches cut into the top. You may need to adjust the height and notch depth to get them to work on your specific build.
We include 16 brass round-head Phillips screws for mounting (2 per nut).