The PT-6143-00 Black TUSQ XL is made for boosting your guitars tone and performance. This precision-engineered nut is made with a specially formulated material that couples the strings' vibrations to the neck and brings out the hidden harmonics and richness in every note. It is based on the highly resonant TUSQ manmade ivory but is impregnated with PTFE to improve the tuning performance of the guitar.