Fender "Sphinx Glides" for amps. Big ones as found on recent models, measure 1.25" diameter, approximately .497" tall, nickel plated steel cup with rubber insert, set of four with screws (original Fender glides from the '60s-80s measured 1"). While these new glides are larger, they do 'retrofit' the old amps and are the best currently available part. Genuine Fender 0993900000. UPC 717669448752.
Photo does not reflect current Fender packaging.