The Plexidor PDWALLSMBR Bronze Wall Mount Pet Door Unit - Small can be installed into brick, block or cement exterior walls up to 12-inches thick. Using an aluminum tunnel which connects the interior and exterior frame, the Plexidor PDWALLSMBR will not rust and has no sharp edges to snag your pet. The Plexidor PDWALLSMBR uses unique, shatter resistant, dual thermo-pane Plexiglas panel that opens with a gentle push and automatically closes tight without banging. Using a snug-fitting high density nylon weather seal, the Plexidor PDWALLSMBR door panels are designed to provide superior draft-control, keeping heating and cooling in the house. The Plexidor PDWALLSMBR interior and exterior frames are made from heavy duty anodized aluminum that won"t rust, bend, crack or warp. Features: * Rigid, high-impact, insulated and shatter-resistant panels do not require costly vinyl replacement flaps and create a window for your pet * Panels open smoothly with gentle push and close automatically allowing large and small animals to use the door with ease * Designed for walls that measure up to 12-inches thick; Large unit will fit exactly between 16-inch on-center studs * Anodized aluminum interior and exterior frames won’t rust, crack, or warp * Use for cats up to 24 pounds and dogs up to 9 pounds * Keeps out unwanted guests with cylinder lock * Opening of 6-1/2-inch Wide x 7-1/4-inch High * Cut Hole of 8-3/8-inch Wide x 10-1/8-inch High * Overall: 10-inch Wide x 12-inch High * Security with lock, key and steel security plate * No replacement flaps required * Highest energy efficiency What"s In The Box: * Plexidor PDWALLSMBR Bronze Interior and Exterior Frame * Aluminum Tunnel Pieces * Installation Instructions * Mounting Hardware * Two Keys * Lock * Steel Security Plate Not Included