6x unused casters for sale, $5 each. Service Caster Corp. swivel casters with 4 inch thermoplastic rubber wheel featuring Total Lock braking. Total Lock brake solidly locks both the swivel and wheel, providing an exceptionally sturdy base when engaged. The wheels perform well and smoothly on most surfaces. It will also not mark or mar surfaces. 200lb capacity per caster.

Wheel Size: 4" x 1.25"
Bolt Hole: 1/2"
Mounting Height: 5-1/8"

I'll cut you a deal if you buy more than one. Pick-up at Oak Creek or on campus.