This key safe box has 4 digit combination code & emergency key; It allows to set 10000 combinations at most, you can set your own access code and change it regularly to improve security, making it hard to crack; The emergency keys can provide more convenience in case that you forget the code . The capacity of WACCET's key safe box outdoor is big enough (inside size approx. 4.5 * 3.7 * 2 inch) to place house keys, office keys or other large car keys; And you also can storage some small things if needed, such as credit cards, ID cards etc. .This outdoor lock box comes with 4 screws and 4 nylon expanding wall anchors to ensure that the Key Safe can be mounted on any solid surface. No fuss or need extra work to have a box drilled into wall at much more expense. .Our combination key box is made of strong, heavy duty Aluminum alloy material, which is waterproof, non-corrosive and weather-resistant. Perfect for outdoor mounted.