San Francisco Municipal Railway token.

I took this vintage MUNI token and turned it into a pendant.

The token is a little less than 3/4" (18mm) in size and has a sterling silver bezel. It's open backed, so you can see both sides.

It's on an 18" sterling silver chain with a lobster clasp.

Little history:
Introduced in the 1940s, the dime-size tokens have been unavailable to the general public since 2005. Muni sold these little coins in bags containing ten, and made it easy for passengers to drop one little coin instead of multiple quarters or dollar bills into the farebox. Even better, the tokens were good for life (similar to "Forever" postage stamps). When Muni sold the token bags, each token was 25 cents less than the adult cash fare, a great bargain for those who ride Muni on an infrequent basis.