Combination Lock Box uses three 2-letter pairs to create a 3-letter combination code Like other VaultLOCKS® Alpha Lock Boxes, our 26-letter combination lock box hangs easily on a door knob, railing, fence or pipe to store door keys right where they’ll be needed. The difference is that each of the three tumblers contains every letter of the alphabet in 2-letter pairs, so it works like a 3-letter-code lock box (or maybe you’d call it a 6-letter code, but you needn’t remember both letters on each tumbler). For instance, A-B-C and Z-Y-X both show up as AZ-BY-CX. Change the combination as often as necessary. No tools needed to install this 3-letter-code combination lock box; enter the combination, then pull to open the key box, lift the shackle and hang. Shackle has a scratch-protection sleeve, and a door guard rubber bumper to protect surfaces. Black.