City letter carrier substitute cap badge
U.S. Post Office Department City Delivery Service wreath-style cap badge with missing horizontal tension pin on verso. Nickel-plated "SUB" surmounts metallic wreath without bow. The word "SUB" indicates use by a substitute letter carrier.
The badge shown met department specifications. The badge is made of German silver, a metallic element containing copper, zinc, and nickel. The Post Office Department chose this metal because of its hardness and resistance to corrosion, an important consideration since the letter carrier's work constantly exposed the badge to harsh and fluctuating weather conditions.