first popularized by Steve Vai. Floyd Rose or Floyd Rose licensed locking tremolo units are available factory fitted on many guitars, as well as complete aftermarket retrofit kits. Fitting the correct kit to a guitar already fitted with a compatible tremolo may be quite straightforward; on others a high level of woodworking skill may be required, or it may not be possible at all. The Fender Deluxe "Locking Tremolo" (better known as Fender/Floyd Rose) is essentially a modified American "2-point tremolo" bridge with locking saddles and pop-in arm. Designed by Fender and Floyd Rose himself, this type of tremolo bridge was introduced in the early '90s on the Deluxe Plus and Ultra series guitars. The concept is primarily intended for guitarists searching for the features of a locking tremolo system without the need to perform routing on their instrument. Nowadays, the Fender Deluxe tremolo is available on American Deluxe, Plus, Ultra Series and many Custom Shop guitars. The whole assembly also includes a set of locking machine heads and an LSR roller nut for optimal tuning stability. Floyd Rose also produces complete guitars with their tremolo systems - most notably with the Speedloader system, which eliminates conventional peghead tuners, leaving all tuning to the bridge end of the strings. They accomplish this without sacrificing stability by requiring strings that are produced to extremely fine length tolerances, essentially having two ferrule ends and no tail. the Speedloader system is the latest Floyd Rose design, but has yet to catch on to the degree Floyd Rose's original tremolo did. In 2015, the company began the commercialization of the FRX surface-mounting locking tremolo system, designed to fit exactly on Tune-O-Matic bridge guitars, but with a locking nut that is fastened to the truss rod cover. This model resembles the Washburn Wonderbar in that the springs and strings do not go through the body, thus eliminating the routing necessary to install the classic Floyd Rose tremolo in classic, fixed-bridge electric guitars. Locking synchronized One of the most simplified ways to have a double locking tremolo system without making any major alteration to a solid-body electric guitar can be done by using a modified American Series 2-point synchronized bridge with locking saddles, a set of locking machine heads and a low-friction LSR Roller Nut. Fender's version of this system is also known as Fender/Floyd Rose (Fender Deluxe Locking Tremolo Assembly), as it was developed in