High power broadcast feedlines are usually pressurized with dry air or nitrogen gas to lock out moisture (which would lead to a Very Expensive Problem). The Andrew/Commscope pressurization gear for doing this has weird tubing fittings on it for the air hoses that hook up to the feedlines. I tried doing a job on one of these systems using little brass tubing fittings from Home Depot and it just didn’t all work right, it was a pain in the /dev/ARSE to get everything to stop leaking. Come to find out, well… The fittings are actually a different system – Parker Poly-Tite.They’re apparently most common in dental office equipment and car washes.
Thank you, Dan Houg, for solving this mystery.