Dimensions: 43.21 x 4.65 x 8.435 mm Blank Radius: 12. Suitable for many Gibson-style guitars, acoustic guitars, and basses with a 3/16 (4.8 mm) deep saddle. Black Tusq XL is a specially developed material that intensely transmits the vibration of the strings to the neck of the guitar, enhances overtones, and overall makes the sound fuller. It is based on the highly resonant Tusq material but is additionally coated with PTFE. PTFE is an extremely slippery substance that prevents the string from getting stuck in the saddle, resulting in significantly improved tuning stability.