Product review (5 stars): Hard-to-Find Product at a Good Price
I needed an oval cross-section vent to fit in an interior two-by-four wall (round is too big).  I could not find the product locally in the big-box stores, so I ended up paying additional for shipping (my fault for not trying to locate it earlier).  However, the product itself was reasonably priced and of good quality.  In the end, this vent was worth every penny; it resulted in an excellent and safe installation.