EVH D TUNA Red 5550121466 The EVH D-Tuna is a unique patented device that enables players to drop the E to D and back in an instant. D-Tuna has been standard equipment on Eddie Van Halen s personal guitars as well as signature series locking tremolo-equipped guitars since the early 90s. Since then thousands of D-Tuna s have been sold all over the world. D-Tuna is proud to be endorsed by many professional players such as Warren DeMartini (RATT) Michael Wilton (Queensryche) and Dave The Snake Sabo (Skid Row) just to name a few. Bottom line...It s simple to use and it works.