A postage meter is a device that produces an imprint that is a substitute for both the postmark and postage stamp.

The PB code identifies the meter manufacturer: Pitney Bowes
The letter O before a meter classification indicates that meter text includes "U.S. OFFICIAL MAIL."

Code PB1

(Example Needed).

Code PB2

(Example Needed).

Code PB3

(Example Needed).

Code PB4

(Example Needed).

Code OPB1

(Example Needed).

Code OPB2

(Example Needed).