My husband is a landlord who constantly replaces locks with different units and the new smart key product by Kwikset Smartkey, Re-Key deadbolt is an answer to prayer. He can leave the same low profile Matte Black deadbolt on the apartment and with the innovation of the new smart key he can reset to any set of keys for the lock that he wants. One tenant can leave, and he can just push the smart key in the insert hole and the deadbolt lock will adjust to any new key that he will use. Lifetime warranty is comforting and the lock set is solid and easy to install. It comes with a set of keys to start with and then the new key he wants to set will slip right in and reset to that key’s contours. Great concept and low cost is a bonus too.