Product review (4 stars): Nice n quite
Very nice unit.. reasonably quite... Been using for a month.
First, it came beautifully packed; no damage in transit. packaging is so good, I can't imagine how it could get dings at all a some have complained earlier. Maybe they fixed the issue. But Five start on packaging.
Power button is only to turn the fan off. press twice it turns fan off immediately; press once it turns it off after a full minute timer delay - a great feature.
LED lights do protrude out about 4 mm under the hood and do shine in your eyes. Take them out and apply a little metal duct tape to mask the edges or just go to any HW store and buy a replacement these are common two prong hood lights also found in some track lights. Can get LED for $3.
The stack/chimney on top is just a cover for the 6" duct, It has two pieces each 17.75" which telescope inside each other and can be separated if smaller length is required. Min length17.75" ..max length 34". If lesser needed you will have to cut .. try heavy gauge metal shears or got to any local Fabrication shop and have it cut. For Greater than 34 you will have just match and buy extra lengths from somewhere on web.
Do not use the flex 6" Duct that comes with it - it is probably the reason for noise many people complained about. Use 6" solid metal ducting and tape it well with foil duct tape (lasting) and top it with guerilla tape for strength. In All ducting joints male end MUST face/point towards the exit/exhaust point to exterior. Never use smaller than 6" duct  in any place even the exterior Duct wall cap must have same cross section area as 2x Pie x 6" = 38 sq inches. Many hardware stores sell caps which have smaller opening at the end and this may cause back pressure and noise. We bought Braun 843BL.
The design for stack attachment on top of hood is absurd. It needs to screw stack from wall side but after you have attached the solid duct to the top of the Hood and hung the hood on the wall hanger you cannot reach it - it is against the wall. Now with the provided flexible duct you may be able to do it; but do resist that temptation if you want quite running fan I just drilled a couple of holes from the sides and none the wiser.
Another problem is that the attachment ring to receive the 6" Duct does not take the female/receiving side of the solid 6" duct - too tight. Again do not give in to temptation to use the provided flex tubing - buy a 6" duct connecter - it is 4" long piece of 6" duct which has male / insertion ends on both sides.
The dimensions of the hood funnel are provided in the picture with a rough diagram.
29 1/4" wide, center it on wall - level it - mark where you want the lower the lower edge of the hood to be (28 to 32 inches above stove top). Now measure up 9.5 inches above the marked hood bottom. This will be the top edge of the hanger piece with has four screw holes ...if none of these fall on  a stud , fix a 4x1 piece of wood across connecting the two adjacent studs and nicely fasten the hanger plate to it. Hanger plate has reverse hooks on which the hood is just hung that's it. Then, you attach the 6" duct at the top of the hood and next you attach the chimney cover to the top of the hood and to another hanger installed at the top.