Duesenberg Z-Tuners 3+3 nickel. Ratio 18:1. Comfortable string pulling and maintenance-friendly technology! The strings are simply pushed completely through the mechanics. The string end is as usual, but cut off on the headstock back. Small fingernail press so that the end disappears back inside (no risk of injury from sharp string ends). Then cranked short, and the string is in tune. Easily be disassembled to grease the gear. 10mm bushing diameter.