GraphTech Tusq Nuts

Graphtech TUSQ - Man made ivory. 
'Tusq transfers the optimum tone frequencies from the strings to the guitar top to pruduce crystal clear highs and big open lows. Precision engineered under high heat and pressure, TUSQ is 100% consistent from piece to piece unlike natural materials such as bone and ivory. Rich, full tone and harmonic content and sustain are what you can expect from TUSQ - trusted more by guitar builders and players than any other nut in the world'