912 Diner Coffee Mug

Anchor Hocking 912 Fire King 350 Made in U.S.A. Anchor Hocking was founded in 1905 by Isaac Jacob Collins in Ohio. Collins' goal was simple: to make glass bakeware that was accessible. More than 100 years later, the brand has evolved from glass bakeware into other glass products that include food storage, serveware, drinkware, mixing bowls, and more.

https://www.worthpoint.com/worthopedia/anchor-hocking-912-fire-king-350-mugs-75748753