I've needed something like that since way back in the late 70's when I started working on planes. Always said we needed a law that engineers had to WORK on things in the field, 2 years out of every 5.
A few years ago Weil-Mclain was at a trade show and they were giving these out as promotional items. I couldn't figure out why a boiler company was giving out bats. Now after seeing the instructions it makes perfect sense.