This numeric lock box hangs easily on any door knob, fence or railing Stores a conventional door key where it’ll be available to whomever you give the combination. Since it’s a home lock box, you’ll get more combination code choices than a 3-digit home lock box. No tools are needed to install this numeric lock box for key; just open the key box, lift the shackle and hang. Scratch-resistant shackle, with rubber bumper that protects door surface. Black. 4-digit lockbox has a numeric combination preset to 0-0-0-0, but you can set your own combination code, and change it, at any time.