Gap gauge. A metal wedge-shaped gauge marked with '1/16', '1/ 8', '3/ 16' and '1/4' on one side and '.02', '.04' continuing up to '.22' on the other side. It has a hole through it at the thickest end of the gauge. Used for checking the gap between plates which were to be welded.

In a small box with three other gauges marked EQS0507, 0509 and 0510.