I have dived Cooper hoses on my Mk 15.5 for quite a while. After more than a decade, they are in need of a refresh, so came here to see where everyone sources theirs. And that was when I found some "contraindications" on Cooper hoses underwater. Why would the US Navy say, use Cooper hoses for testing their latest 3d-printed titanium Mk 29 hybrid hard hat rebreather, if Cooper hoses weren't designed for use underwater?