Set screw fixing, fits standard 1/4" diameter solid shaft pots on vintage and modern amplifiers and guitars. Introduced on tweed-era Fender amplifiers, also used on '59 Bassman®, Blues Deluxe™, Blues Deville™, Hot Rod series, Prosonic™, '57 Twin®, '57 Band-Master®, EC Series, and Bassman TV series amplifiers Brand New. Genuine Fender 0058164049. UPC 885978452200.