Florance KK-A USPS Approved Key Keeper Lock, Aluminum Without Key Retractor & 24" Chain Recessed, Key Retractor 24" Chain Not Included!!! Prepared to accept a postal lock installed by local post officials to distribute mail in accordance with USPS regulations. Loose key type prepared for U.S.P.S lock (Standard), Permit the use of automatic-locking street entrance doors for apartments. Maintain security, but allow mailman to enter the building to distribute mail in conformance with U.S.P.S. regulations. Florence Key Keepers securely provide access to important keys to only those authorized to use them. So whether you need to provide access to a key that lets your letter carrier into your secure mail room or any other part of your facility, a Florence Key Keeper provides a simple solution.