I just wanted to add to this --fakes can be near perfect in appearance. A number of years ago Black Diamond had to put out an advisory on one of their pieces of mountain climbing gear because someone was making an exact replica of their climbing hardware...but with substandard metal.

Everything matched, with laser cut serial numbers and everything. The only way they could ensure it was real was by material testing, or known purchase from an authorized dealer.

Years ago there was a decent chance amazon had the real thing, but now I'd avoid anything that can potentially kill you