Digital Keypad/Codelock that can be used to replace an exsisting rim cylinder. Battery operated (4 x AA batteries supplied) using a 6 digit code (up to 50 different codes can be used using a master code). Batteries are stored in a housing approx. 70mm x 70mm x 20mm which can be attached to the inside of the door or morticed into the edge of the door. The turn knob freewheels when locked. Suitable for extenal use.