It's an "Inmar" (short for "Inland Marine?"). They import out of California. Used to be "JP Marine." I know the pressure release valves they use are Leafield. But that's a mystery too. The pressure release valve says 3.2 psi but the inflatable is rated for 3.6 psi. When I inflate they start to exhaust at 3.8 psi I can hear them. Could be a simple typo whoever was making pressure release valves that day?
Yes...the 12.5' 380 I still have never did vent to my knowledge. Found the tubes at 4.6 psi one day in the hot sun.