Vietnam War GI Zippo lighters. Their history and markings/date and month codes. How to tell a real Vietnam Zippo from a counterfeit:
Zippo lighters: From 1931 to the present day, at least 3 different variants of the original flint and wheel Ol' Clicker had been made. Also, three distinct eras of the Zippo is present, distinguished by how the company dated and coded new lighters out of the factory. The most current dating and coding system uses the letters A-L to indicate month and the last 2 digits of the year from 2000 onward. So an "H, 14", on the bottom of a current production Zippo means that it was built in August, 2014, like the one I currently EDC...
Edit: Month correction. August.