Bright Nickel plated steel. Essential parts for guitar and amplifier restoration, building and repairs; fits the CTS pots and Switchcraft jacks found on those great '50s-present USA guitars and amps exactly. Keeps those vital parts tight to your chassis/circuit, cleanly grounded and working as they should. I measured .685" outside diameter, .387" inside diameter. Brand New. Genuine Fender 0016436049. UPC 717669068929.