External dimensions (H x W x D): 12.4 * 8.3 * 4.15 cm; Internal dimensions (H x W x D): 9.2 * 7.5 * 2.6 cm. The U-hook is 5 cm high and 4 cm wide. The key box has a large interior that can hold up to 5 keys or 3 large keys. You can also use cards, readers, etc. Your key box features a waterproof sliding lid and waterproof rubber cover to protect the dials from dust, rain, snow and ice. Store your keys safely in our 4-digit combination key box. Resettable 4-digit combination for maximum keyless convenience. You can set and reset your own personal password, with 10,000 password options with custom combination codes. Get spare keys and give them to your loved ones and family members when you are at work. After resetting the password, it is advisable to take a photo for safekeeping, otherwise it will not be possible to open it if you forget the password. Easy installation (mounting kit included in the package). Metal construction for durability. Can be fixed to the wall with the provided