The numbers and letters on personalized Zippo lighters indicate the date the lighter was made. The letter on the customized lighters is representative of the month A=January, B=February, C=March, etc. and the two digit number indicates the year 01 stands for 2001, 02 stands for 2002, 03 stands for 2003, etc.

What are the numbers on the bottom of a Zippo lighter?

After July 1986, Zippo began including a date code on all lighters showing the month and year of production. On the left of the underside was stamped a letter A–L, denoting the month (A = January, B = February, C = March, etc.). On the right was a Roman numeral which denoted the year, beginning with II in 1986.