If you own a giant breed, or smaller, this is the one you'll want. Large and roomy, quality made. The two separate flaps are clear so the dogs can see to the other side and not run into each other The space between the two flaps means increased Weatherproofing and the flaps don't catch on each other, nor get caught up on dogs legs. I installed in a bedroom wall and attached a dog house to the outside wall so the large opening isn't visible to neighbors. This increased security and prevents wind from blowing through.
I choose to build my own frame in the wall rather than buy the kit. Easy except I couldn't find screws long enough to attach both sides. So I added an extension and cut thread to size. See picture

It works reasonably, but definitely has a few issues.
The biggest problem is that the insulating brushes on the side are stiff enough to catch the door after the pet goes through, and prevent the flaps from closing. This leaves a reasonable gap for air to pass through, and completely voids the whole purpose of having a double-flap door for weather insulation.
Another issue is that the magnetic holders on the bottom of the door were very stiff and had to be lubricated before they would work as intended by adhering to the flaps once they closed.
Other than that, the door works reasonably. Would be nice to have the ability to lock the door without having to insert an entire panel (which is annoying to store when not in use), but that probably isn't feasible with the soft plastic used for the flaps.

My dogs LOVE their new door. Took a bit to train them but once they figured out they could go outside anytime they wanted they was all about it. Easy instal and instructions. We bought the XL for our husky and pug, our Maltese will even use it if you hold the flap up for her. The Maltese thinks it's a glass door or something I guess... We have a security camera set up that lets us know when there is movement in and out of it and the dogs use the door all day long.

We got this + the telescoping kit so we could install in the wall. Right now, the flaps are off as its summer and our pets are getting used to it but we'll be adding one flap back on. We have a 5 lb dog who's WAY too spooked to go thru 2 flaps.

I love the VERY clear flaps on this.

What would I change? The magnets on the flaps can stick together - that's a deal breaker for a shy pet- so I recommend just using one.

I'm also going to find something not slippery to put on the telescoping part (the flat shiny "tunnel" floor) because it's a bit slick for our dog, who BLASTS through this as if his very life is in peril. Don't worry, he's done this with every pet door we have had!

We got the medium, I wouldn't go smaller for our pets: a 5 lb dog, 7 lb cat and a 15 lb cat. The dog would NOT go thru a door he had to squeeze through.

Owned this now for 17 months. I wanted to wait a while before giving a review. I would definitely do 5 stars.

1st I own two Australian Shepherds. One is 80 lbs, the other 70 lbs. I live in Northeast PA, I work 5 days a week, and have this door mounted in my storm door in my kitchen. The dogs have freedom to go outside in the fenced in yard from 6:30 AM to whenever I am ready for bed. I have gone through 2 single flap doors in 2 years. I got one season out of each. One of witch was over $100. So when I bought this I was a bit skeptical but wanted to try.

My main complaint of the single flap design, other than they fell apart, is in the winter when the wind blew it would blow the flap wide open. Not good when it's in the single digits outside. This door really held up to the wind. It even survived the blizzard we had in March. It did start to actually freeze up from melted snow re-freezing on the flaps. But it was a blizzard.

So long story short, my dogs run through this door probably 50 times a day, two dogs, that's 100 or more times the flap is used per day. And it still is in good shape 17 months later. I should get one more winter out of it, maybe more. But for the abuse it takes I would buy another in a heartbeat and recommend it to anyone.