The PQ-M169-00 is a TUSQ slotted nut specially designed to be used on Martin style guitars and others with similar specifications. TUSQ nuts and saddles have rich tone without the inconsistency found in ivory, bone and other natural materials. Bone and ivory have hard and soft spots (grain) throughout each piece, hampering consistent transfer of vibrations to the guitar top. TUSQ nuts, saddles and bridge pins are designed to transfer the right frequencies more efficiently from the string to the guitar body.