I ordered the Z line 48" to go over my 36" island gas cooktop.  Once it arrived, I opened everything up and determined how to install it.  We previously had a downdraft so there was no existing ductwork.  We live on the coast, so with constant storms, it is almost impossible to find a company to install something for you, and if they do give you a quote, you may have to sell your car to pay them.  After 2 ridiculous quotes and lengthy lead times, my wife and I  (both in our sixties) installed this unit ourselves!  I must say, it looks great and works great.