This numeric lockbox hangs easily on any doorknob, fence, or railing. Stores a conventional door key where it’ll be available to whomever you give the combination. Since it’s a home lockbox, you’ll get more combination code choices than a 3-digit home lockbox. No tools are needed to install this numeric lockbox for the key; just open the key box, lift the shackle and hang it. Scratch-resistant shackle, with a rubber bumper that protects door surface. 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.