top nut for electric guitar, unbleached bone, 42,5x6,5x3x1mm, pre-filed, spacing 34,6mm Pre-filed string slots. Stringspacing 34,6mm. Flat bottom. This nut is made from unbleached bone, a long-time favourite of many luthiers. The slightly self-lubricating properties of unbleached bone as opposed to the very white bleached bone are a good reason to use this nut material. When polished, the looks of unbleached bone are very elegant and will add class to your guitar.