This is a 6pc set of beautiful black sealed-gear guitar tuners, set up for "6-in-a-line right" alignment, such as is seen on Fender(tm)-brand electric guitars such as the Telecaster(tm) and Stratocaster(tm).
This set of machine heads feature screw-in style bushings, with a single screw used to mount them from the back. The bushing screws directly into the main tuner housing, through the headstock, for a snug, secure fit. The washer goes on the front of the headstock between the bushing nut and the wood, for a stylish, distinctive look. We ship these with the washers and bushings already in place, as shown in the photos.
These tuners are intended for headstocks that are between 0.46" (11.72mm) and 0.65" (16.5mm) thick. A good rule of thumb is 1/2" to 5/8" thick, with 9/16" being the ideal. Trying to use these with thicker or thinner headstocks may not work.
These great tuners can be used on cigar box guitars, regular guitars, diddley bows, banjos -- pretty much any stringed instrument that can be set up with a standard machine head!