This is an authentic antique brass lock cylinder and matching key manufactured by the Donnell Safe Co. of Chicago, Illinois. The key is clearly stamped with a patent date of July 26, 1898, along with the company's name and location. The reverse side of the key bears the serial or part number 3238. The lock cylinder features a threaded body and a geared base ring, typical of inner door safe mechanisms or specialized deposit boxes from the turn of the 20th century. The cylinder housing is also stamped with the number 26.

The Donnell Safe Company was formed in the late 1890s following a complex legal dispute involving the sons of Joseph Hall (of Hall's Safe & Lock Co.) and the Herring-Hall-Marvin Safe Co. This lock represents a specific era of Chicago-based safe manufacturing before the company underwent further name changes.

Condition: The set is in Very Good/Original condition. Both the cylinder and key display a heavy, unpolished brass patina with standard surface scratches and tarnish expected from antique hardware. The key inserts and turns within the cylinder, though the geared mechanism is untested in a complete safe environment. There are no structural cracks or missing components visible on the main body.