The Graph Tech TUSQ XL Gibson Adjustable Nut replaces the brass zero fret nut installed on 2014/2015 Gibson guitars (it does not fit 2016 onwards models), it drops in to the lower portion of the existing nut giving you a high quality, traditional non zero fret nut made from TUSQ XL and also maintains the heigh adjustment feature. TUSQ XL is impregnated with PTFE for permanent lubrication ensuring strings don't bind in their slots during bending or tremolo use, improving tuning stability and reducing string breakage. The TUSQ XL material is harmonically rich and transfers vibrations efficiently to the guitar, as a man-made material it is consistent from piece to piece with no hidden soft spots associated with bone. Graph Tech nuts are supplied slightly oversized to allow for final fit and shaping (material works easily with fine sandpaper).