top nut for electric guitar, Stallion model, unbleached bone, 44x6x3,2mm, pre-filed The string slots are pre-filed, the string spacing is 35,2 mm. 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.