The SPCY521 is a metal back box for flush mounting the SPCK52x Compact Keypad into concrete walls. When used with the SPCY520, this product allow the Compact Keypad to be installed flush into the wall, providing a slim and elegant appearance with full tamper protection. Using screws or nails, the SPCY521 can be secured at the back or sides to any wall. In addition there are foldable wings on the sides of the product allowing it to be set in concrete wall.