The DiMarzio 500K Long Shaft Potentiometer is designed to replace pots on guitars, such as certain Les Pauls, where the shaft needs to travel 3/4" to meet the control knob. Here"s a list on some guitars that do require a Long Shaft (3/4") Potentiometer: Les Paul Standard, 1977-current Les Paul Custom, 1977-current Les Paul Deluxe, 1978-current Les Paul Pro, 1977-1982 Les Paul Studio, All Years Les Paul Classic (1960), All Years Historic "68 Cus. Reiss., All Years