Product review (5 stars): Anti-Corrosion Coated Steel
The kit I received worked great.  It's good they included the 3/4" adapter (as well as two 1/2" ones), since I needed that to connect the supply side.  The hose I received was steel with a yellow protective coating.  Your hose will look yellow instead of metallic like the picture.

The included thread sealant worked just fine - note you only use it in two places, not everywhere there's a thread.  The leak detector liquid was kind of hard to get in the right place once it was installed.

Installation will take two wrenches that handle at least 1-1/8" or so, can't remember exactly.  I really had to crank these suckers on to get a leak free seal on my supply side - no limp-arming it.