The picture shows a view of both sides of this Old AC Spark Plug Advertising Premium Spark Plug Gauge. It is made of steel and has recessed lettering and numbers. On one side it has "AC" at the top and gauge measurements. The other side reads:
AC SPARK PLUG GG-14 GAP GAGE
It is not dated but believed to be old. It measures 1" x 2-3/8". It appears to be in near mint to mint condition.