This is a shim kit for use with Overhead and First Class Parlor guitar. It works with models such as FF412, FF422, FF412C, FF422C, and all similar models with Narrow necks (those with “N” as the last letter in the Product Number).
These shims can be used temporarily and can be reconfigured according to how your guitar changes with temperature and humidity. They can also be glued for permanent installation.
