Witten Automatic Vent B-EBLACK(MB) "Energy-Saver" Foundation Auto Vent 8" X 16"- Black

An excellent product, easily installed, and providing a very fine varmint barrier!

I bought three. Before installing, I tested them in my freezer. They are supposed to be fully closed at 35 degrees, so a freezer at zero degrees will more than do the job. You must stand them perfectly upright in the freezer - the same orientation as when they're installed, otherwise even a good one won't work properly. Apparently, the louvers are somewhat gravity assisted. After 30 minutes in the freezer, one of the three was still wide open. I exercised the louvers and found that the mechanism was sticking (hence, 4 stars). After working on it a bit, I found a rough spot on the bimetallic spring and fixed it. Then I took all three out of the freezer and sat them upright in front of a floor fan - the temperature was roughly 80-85 degrees (they are supposed to be fully open at 75). All three opened okay. Installation orientation is critical. Look for the word "TOP" molded into the plastic. The four screws are 3/16" hex-head capscrews. Tightening them with an L-shaped hex wrench is a lengthy process. Fortunately I had a 3/16" hex to 1/4" socket drive adapter and a 1/4" drive universal joint, so I tightened them with my cordless drill, which took less than 1 minute for each vent. Note that the temperature trip-point is adjustable, although I didn't need to do so. There is a nylon screw on the end of the vent which twists the bimetallic spring mount, the same way as old spring-type thermostats worked.

Placed these all around my house with a crawl space. Fairly easy to install and seem to open and close as expected, so ordered more for another house.

work good, test in the freezer, easy to install and they look good. same price as lowes except with amazon i didn't have to go and pick them up and hey, free shipping

Seem to work like they should. Only time will tell. One came in broken but was very easily fixed. *Update: We finally got to install all of them and we found a second broken vent that cannot be fixed. I would suggest that you inspect all of the vents very carefully as soon as you receive them. We should have returned the first broken one instead of fixing it ourselves. We might buy these again but now we know to completely inspect all of them upon arrival! ANOTHER UPDATE 12/8/16: These DO NOT WORK! I do not like leaving negative reviews but it's pretty important that these work like they should and they don't! We live in Texas so it doesn't get cold that often but right now it is 32 degrees and these things are wide open! It will be in the teens and 20's this evening and tonight so I guess we will have to find another way to protect our home and throw these in the garbage! DO NOT WASTE YOUR MONEY! Or your time installing!

Overall great value for the price and rare item that is hard to find in local stores. Important note for buyers - this vent is black, but I was able to paint it into various colors using color spray. Also to test automatic feature - put this vent in your freezer to see if it works before installing. Plastic and aluminum should last for years.

When I compare it to my HD old ones that were installed in 1990, they are basically the same. Over time the bolts corrode and rust so you cannot adjust them and they are hard to remove, This time I purchased stainless steel replacements which hopefully won't rust. Eventually the screen gets holes in it from various creatures trying to get in the crawlspace. Another reviewer suggested adding a finer mesh screen behind the one provided and I did that too. All eight of mine passed the freezer test but when winter arrives will be the real test. If I have to pull them out and tape them closed it's not a big deal since I may decide to add Styrofoam for insulation anyway.

Purchased specifically for the automatic closure feature. Before I installed it, I tested by putting in my freezer. Put in freezer same orientation as if I installed in home. Checked in 1 hour, vents still open. Checker in 8 hours - vents still open. The vent uses a simple thermostatic coil spring so it should work. Not sure why this one did not close.