GraphTech PT500000 TUSQ XL Black Self-Lubricating Slotted Nut, Fender Style TUSQ XL is engineered from the same material as TUSQ and is impregnated with PTFE which is five times more slippery than graphite It has all the tonal benefits of TUSQ, bringing out the hidden harmonics of your guitar all while drastically improving tuning performance TUSQ XL is consistent from piece to piece, and within each piece, to offer you harmonically rich tones without the problems associated with natural materials