The picture below shows a larger view of this Massachusetts Bay Transportation Authority MBTA Employees Credit Union Advertising Pin. This brass pin is not dated but it is believed to be from the 1990s. It is a tie tack type pin and the back section is included. The pin is marked as follows:
MBTA EMPLOYEES CREDIT UNION T SERVING FOR OVER 60 YEARS
The pin measures 1'' wide. It appears to be in mint condition as pictured.