The Holson WAD heavy Duty Caster Board is designed for our range of Amplifier Cases. It features beefy heavy duty casters with integral locking brakes. Thick premium grade plywood base to provide solid and ease of mobility for a variety of cases. The Holson WAD raises the height of your rack system by approximatly 5 1/4 inch (13.3 cm). Great value and extremely rugged caster board.