Luthier Series™ Engineered Thermoplastic Slot Mounted nuts for Fender® Style guitars Are injection molded replacement nuts featuring resonant Massive™ Nut Technology, PEEK 30% GF base parts and Low Friction PEEK 20% PTFE saddle parts. They are available in a variety of sizes, colors, fretboard radius, They are designed to accomodate and string spacing variables. Please check your instrument or ask your luthier to make sure you order the right size.