Traveler Guitar Locking Tuning Machines are built to be a drop in replacement to the existing tuning machines on existing Traveler Guitars. Models that are compatible with the Locking Tuning Machines are: Ultra-Light*, Ultra-Light Electric*, Ultra-Light Lefty*, Pro-Series, Pro-Series Mod-X, Speedster Series, Speedster Hot Rod Series, EG-1 Series, EG-2 Series, and Travelcaster Deluxe guitars. Traveler Guitar Locking Tuning Machines are not designed to be used with Nylon Stringed or Bass guitars. These tuning machines can work on other guitars, but check the specifications to be sure. * Ultra-Light Model Guitars with a Serial Number containing an "S" are excluded.