First time browsing this thread, and I must say, the effort your couplers require and the ease of which they disconnect safely makes me very interested to try them. But to be honest, I've looked at the prices of Milton and prevost connections, and I couldn't justify spending that to purchase air fittings. I understand the costs accociated that drive the price to the level it is, but the fact remains, that's a fair amount of money to set up a whole shop air system. Money that I could easily put into more valuable projects.
I use old H. They are not easy to connect especially at 120 or 130 which is our static air pressure. They hold, they last and they don't leak. Can take them apart and flip the washer over.
I have a lot of stuff in a broad system, not GM plant big but a lot of stuff including good portable on service truck. Only rarely do I use 3/4 gun but blow a couple lines out and only minor use from it so,,, I have 1/2 on a reel on the truck and all 3/8x50 in the shop. This fitting is a little bigger but it lasts and is good for all my tools, use it to blaster etc. My blaster would not noticeably be limited with 3/8 but got a 25 ft pc of 1/2 and could use a section of it around the regs and reels in the shop but its really rare. I just aint wrenching on other peoples big trucks and equipment, am very 1/2 dependant but can do 999 or more out of 1000 that I got to get a heavy gun for.
I don't have hydrants and hot sections of hose I have to move, its super rare I need an extension. When I was a sprout used to do that, somewhat had to and saw it done that way but as I tailor, fit and tune can get away from a lot of problenms I used to have orr learn to cope.
I was a little slow with some stuff, hung hoses way before I got reels and didn't think it was such a deal but many of the guys here can afford the additional equipment.
What was the point,,,, oh,, yes, I have a fair number of couplers which is some expense. In a home garage, small shop could easily service most the air with a reel and a whip, maybe one each and cover it all. I can repair and paint a car with one hose.
In a simple system that wasn't heavily invested in tools a guy could need as little as 2 couplers, maybe a couple more (I stock some) to make additional equipment. It wouldn't cost much new or replacement, the male or the plugs are cheap.
But till the internet lots of guys make professional careers with common air fittings. I got nothing against new and improved. but there is some obstacle for me to change, the cost and the work.