A common issue with Chernihiv banduras is that the nut gets torn up and causes buzzing issues with the bass strings. The correct fix for this is to have the nut replaced by a qualified luthier, but that can cost hundreds of dollars and likely means that you would need to ship your bandura. This shim provides a quick, affordable solution. Simply loosen your strings, slide the shim beneath the existing nut, align the strings, and tune!
It can also be used to convert a chromatic-compensated nut (where the strings are at different heights) to a straight nut (where the strings are all at the same height).