Basically, these quick couplings solve annoying problem of wrestling with leaky hose connections under pressrue, especially when you're crawling under a machine with mud in your eyes. 2. Our round head push-pull design lets you snap them on or off in under a second with one hand, and the vacuum-plated surfce treatment means they won't corrode after a season in the field. 3. They're rated up to 5000 PSI comfortably handling the flow rates between 30-50 L/min, but the NBR seals (usually good for -20°C to 120°C) aren't ideal for high-temp oil systems above 130°C — just a heads up there. 4. You'll get them in standerd cartons with both metric and imperial threads avaliable, and we keep about 500 units or so of the common 1/4" and 3/8" sizes in stock right now (confirm lead time for teh oddball specs).