Vintage/Old "New York City Transit System" Steel Badge/Pinback, Ca.1940s?

Description

Offering my late uncle's "New York City Transit System" badge or pinback; #17427.
Uncle Robert was a conductor from the early 1900s until retirement around 1950s.  I imagine this badge to be circa 1940s, but some of you may know better.  I believe the number to be fairly old.
Most likely made of steel.
Size: 2" Diameter
Very interesting railroad, subway system, train, collectible.
Condition is Very Good with only japanning loss on the numbers and letters.  Otherwise shows very little age wear.
No real scratches that I can see.
Pin with "Mickey Mouse" ears clasp, works as it should.
No breaks, damage or repairs.
Please see pictures and ask questions before bidding.  I'm proud of my 100% positive
eBay record and want you the buyer to be happy with your purchase.  Please see my other listed items.
No international bidding or shipping!  No shipping outside the continental U.S.
I will be away from July 19 to 24; so, all shipping will take place first thing the following week
.