Mechanical code lock construction, no need power supplier, durable and stable. 4-digit code for maximum and safety, set your combination with ease. Waterproof cover to protect the dial from bad weather. The lock box packing includes screws and anchor to mount the lock box on wood, steel, tile, drywall, and more. There are four pre-drilled holes in the back side of the box for easy mounting. Key box has a spring structure. Enter the correct password, dial the button, the key box will automatically open, do not need to manually pull, safe and convenient.