The RRWADS, our heavy Duty Caster Kit is built to hold up to pressure! Beefy 3 1/2" Casters with integral locking brakes doubled with a thick premium grade plywood base provide all the mobility you'll need for any Road Ready Deluxe Shock Mount Amplifier. The RRWADS raises the height of your rack system by 5 ". Mobility made easy http://www.roadreadycases.com/pdf/RRWADS.pdf