The PT-6000-00 is a great option to upgrade the nut on your Gibson USA guitar. It has a flat bottom and is pre-slotted for a quick and simple install. Black 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.