This official Fender Stratocaster Volume Control Knob with Cap is for use with an S-1 switch potentiometer (which can be retrofitted to nearly any US and Mexico made Stratocaster manufactured from 1954 to present). The knob features a knurled edge for grip, and it is a great way for you to customise the look of your strat. Will fit 1/4" split shaft S-1 switch potentiometers.