BUILDERS BEST 12634 Roof Cap Flush, 6-8", Black

Good metal to replace cheap builders vents.

Work just fine as a microwave roof top vent with 325cfm

This is a supersized version of their smaller vent caps with 4" and 6" collars. The underside opening is huge: 8" is a minimum vent size and 10" may be possible with a custom flange which you would have to fabricate anyway to achieve a tight coupling. The assembly is well built but needs a good air seal and large volume of air to lift the heavy damper which is ~12" square.

Fits and works great for my 8 inch duct

Needed a 7 in adapter, but could not find one anywhere. They need to make the adapter and size an option from the main detail page.

Seems high quality.

Had a rough start during shipping but very pleased with the product and the Merchant thereafter

I've had this in place over a year now and it works perfectly. Sad to say others leaked, made noise flapping with wind gusts etc. None of those problems with this product! I paid a little more, and it was worth it!

This Builders Best product appears to be well made. However beware of the description. Copied directly from the manufacturer, it gives you the impression that it will directly fit a 6"-8" round duct or a 3-1/2" x 10" rectangular duct. It will not. Before purchasing I inquired of the manufacturer if a transition was required. The reply said in part: " No adapter is required for our universal roof cap, part 012634. It is designed to be used with 6" to 8" round duct or 3.25x10" rectangular duct." This in not entirely accurate. The vent simply has a 6-1/2" x 10-1/4" recessed opening. You will have to fabricate a custom transition to make it work. Also, an opening of this size cannot possibly fit an 8" round duct.The vent has a back-draft damper. It is a little on the heavy side so you will need a fan with sufficient static pressure to open it. This is why it receives 4-1/2 stars and not 5. It has a good sturdy anti-rodent screen.I will return this item.