Built by the Budd, Pullman, and St. Louis car companies, they were called "Multis" for short.

Their average length was 170 ft (52 m), making them the longest articulated units ever used in the history of the BMT.

The Pullman-Standard's version was known as the Green Hornet, while Budd's was called the Zephyr, both names being unofficial.

These cars were in production at the same time as the Union Pacific M-10000 and the Budd Pioneer Zephyr for the CB&Q.

The Green Hornet had undergone some slight modifications, and the BMT management hoped to eventually run it in consists with the Pullman-Standard built multi-units.

[1] The unit had been plagued by master controller problems and was only in service for three years before it was withdrawn after maintenance revealed two cracked trucks.

This induced the BMT management to set up a service specially for these units, namely the 14th St.–Fulton St. Line.

In December 1956, the cars were transferred to Myrtle–Chambers service for purposes of cutting their mileage, as was commonly done at the time with all oddball types of equipment.

In February 1958, a few units underwent a one-week stint in Franklin Avenue service (shuttle and on the last day, a Sunday, local to Brighton Beach).