12U, 21-inch Deep Sectional Wall Mounted Rack with Vented Glass Front Door Included. Hinged back double section welded frame construction. 21.65-inch depth. 18 gauge removable side panels with spring latch. 18 gauge cold rolled steel top and bottom. Fan ready perforated top. 11 gauge drilled and tapped front and rear rack rails. Rack U numbers printed on the rack rail. 1/32 rack screws. 1/2-inch, 5/8-inch, 3/4-inch, 1-inch and 1 1/2-inch cable entry knockouts on top. 5/8-inch knockout designed to be used for VHF/UHF antenna. 1-inch x 1-inch rear access knockout for cable entry. Rear door is removable for easy installation.