Abstract: A lock system comprising (1) a first standard size pin tumbler lock mechanism, such as is used, for example, in an exterior apartment door; (2) a second pin-tumbler lock mechanism substantially smaller in size than the first lock, such as is used for securing an apartment house mailbox; and (3) a key having conventional handle and shank portions and a set of notches and projections extending along one longitudinal edge of the shank portion such that the key, when inserted into the barrel of the standard lock mechanism, will render it operable, and such that the key, when inserted into the barrel of the smaller lock mechanism, will also render it operable.

Abstract: A lock system comprising (1) a first standard size pin-tumbler lock mechanism, such as is used, for example, in an exterior apartment door; (2) a second pin-tumbler lock mechanism substantially smaller in size than the first lock, such as is used for securing an apartment house mailbox; and (3) a key having conventional handle and shank portions, a first set of notches and projections extending along one longitudinal edge of the shank portion such that the key, when properly inserted into the barrel of the standard lock mechanism, will render it operable, and a second set of notches and projections extending partially along the opposite longitudinal edge on the shank at its outer extremity such that when the key is properly inserted into the barrel of the smaller lock mechanism, it will also be rendered operable.