I have written on this topic before when talking about our pest proof vent covers. Frankly the only vent cover I will install on a home these days because they simply are the best in preventing pest access to the dryer ducting while still allowing for great airflow from the dryer.
But I must admit even as great as these are, there are still some situations where the need for a little more protection is in order and that is where the defender vent cover comes into play. This might be in an area where limited human access is available such as under a deck or high up in the eaves of a home. Or maybe your property backs to green spaces where the chances of woodland creatures having the time to access the ducting is greater.
The defender is a great addition to a typical dryer vent by adding some very hard metal bars to provide additional protection to the airflow and existing vent cover. But you may ask, “I thought screens over the vent cover were not allowed by code?”, which is exactly the question I asked of the manufacturer. And it seems this particular design has been engineered to not only prevent access from unwanted pests, but was able to be accepted by the powers at be (think building code people) as an effective dryer vent cover.
I have personally installed many of these in areas just as I mentioned above, where there is limited access and have not found an instance where I was not completely pleased with the results. Because I personally guaranty every one of my design and installations, should one of these begin to cause problems, I resolve the issue for free. So you really cannot go wrong with the defender on your own homes dryer venting.