4 Space (4U) ATA Rack Amp Road Shock Mount Case (20" Deep) Rugged 3/8" Plywood with Black Laminate Tongue and Groove Metal Railing with High-Impact Ball Corners 1" Layer of Shock-Absorbing Foam Between Rails and Outer Walls 4-Space Standard 19" Equipment Rack Rails (Front, Back), 20" Deep (excluding lids) Foam-Insulated Front & Back Lids, Slip-Resistant Rubber Feet