Some air hose connectors (the male connectors that fit into the quick-connect fittings) say "automotive" on their package and some say "industrial". What is the difference between them?
Fittings for the female quick-connect usually have o-rings or some sort of rubber seal where you attach them to the hose. The male connectors that fit into the quick connect typically aren't sold with an o-ring in the female end, which attaches to the hose. Is it good to put an o-ring in there?