Looks like a nice kit. from the photos on amazon, it looks like the gauge and relief valve are replaceable if you have to do that. for me, having those fittings and hose is a plus, then replacing the gauge with one that can be calibrated might come out cheaper than buying an expensive kit. even if the relief goes bad, if it's threaded with a standard SAE thread, you can install a tiny ball valve in it's place to use as a relief
of course I'm a redneck engineer lol that's known to make what I have work in situations when I don't or can't spend the big bucks. haha!