Product review (4 stars): it really wroks well
I bought it via Ebay from the same store, since it's a little bit cheaper, ( not sure if the quality are the same, but one sure thing is that Amazon have superb customer service). and buying it from ebay, you're on your own risk.

It comes in one package, with missing at least one screw ( only 3, should be 4 I assumed and based on the simple paper instruction) , I have taken photo of it.
the design is very classic , the made quality is close to Home depot Nutone brand ( $69 and upper $499 depending on models and material).
Installed a week ago and used lightly for a week now,
the biggest thumb up  is that it " sucks" and worked very well, way better than the one I returned ( AKDY brand, which have a  marginal better quality and sexier design, but literally useless in my case and model).
The major concern I have is the longevity of it, because one of the two motors fluctuate in RPM based on my ear either in speed I  or II, and when I upack the product , I did use my hand to test-rotate the blades, one is super smooth, other is not ( subtly touching the frame, I bet). but the above two things  should not be related.

The product can be further reduced in size ( at least in depth for front 1/3,) , the thickness is pretty good and already very thin, you may argue that by further reducing the depth is pointless since it's about cabinet depth. my point is that, by doing so will further decrease the weight of the hood and material it used.
Overall I'm satisfied with the product. it ventilates well with powerful motors and loud but expected and not too annoying pitch sound.  I used it lightly, and hope it will last for at least 2 years or more.  looking forward to seeing their new models, improved function,  ( such as LED light rather than yellowish bulb, improved switch) and much lighter and smaller.
One note for potential buyers like my case, you need to hook an power cord, it does come with an open ends 3 prone wire, but no plug and very short, again usually people directly wired it, and no need for plug in that case, for me it does)