I added this wide angle lense to the rear window of our Winnebago Navion RV in the hope that I can see our tow vehicle while driving...and it does so with great effectiveness! The rear window in the RV is high and without the lense just shows the sky or a semi barreling behind us. When I put on the lense, and positioned the car behind the RV where it would be for towing, the car's presence was clearly displayed in the lense whereas, without it, the car was invisible! I can view the car using my rear view mirror on the windshield.This wide angle lense solved my towing problem perfectly.I am sure this lense will be as effective for removing blind spots in any vehicle as well and enhance driving safety.

We have a Class B motorhome built on a Chevy Express van body and it has always been challenging when backing up because you can't see well what's directly behind you. The rear door windows don't give much of a view. At the recommendation of another, I decided to try a Fresnel lens. I applied this 8x10 Fresnel lens to the lower inside corner of the drivers side rear door window. It goes on the inside of the window, not the outside. Installation was easy. Just clean the glass then mist the glass with water so that it is uniformly wet. Then press the Fresnel lens against the glass using an unrolling motion so as to minimize any air bubbles beneath the lens. You can then work out any remaining air bubbles by pressing them toward the outside edges of the lens. I have rear window defroster leads on my window and I just put the Fresnel lens over these without any problems. I don't plan to use the defroster with the lens in place though.We just got back from a three week trip and I must say that I love this Fresnel lens and would never travel without it in the future. It gives a very clear wide angle view of what's behind my van and gives me a lot more confidence when I back up. Now I can see when I'm getting close to a car behind me in a parking lot and no longer have to send my wife out to guide me. I had been considering installing a backup camera, but this lens is almost as good and without the cost or hassle.EDIT 1/11/2019: I've been using this lens for almost 3 years now and still find it fantastic. Note that It has fallen off the window after keeping my van in storage for the winter. I just re-wet the window and re-apply the fresnel lens and it's good to go for the following season.

I've had this on my Honda Pilot for almost 5 years. I've never had it fall off, nor have I needed to remove and re-install it.Like many others here, I got this to help prevent me from backing over small children. I like this solution over a backup camera not only because of the price, but because it is both simple and effective. It does not require ANY panel removal or modification to the vehicle.I also prefer this over backup cameras because I'd rather be looking out of the rear of the vehicle when reversing instead of looking forward. When looking out through the back, not only do I see what's directly behind the bumper, but I can also see approaching cross traffic better with the wider field of view provided by the three rear windows.The only issue I've had is judging the distance of vehicles following behind me. It did take some adjustment. But I think the extra safety it provides when backing up more than outweighs this minor issue. After all, the purpose of this product is to improve rearward visibility when in reverse.One additional bonus is that it does help me out a bit when parking in front of cars. The low, sloping hoods of most cars make it difficult to judge how close I am to them. The wide angle lens lets me see pretty much where the front bumper and grill are.My brother-in-law became interested in one of these when I showed it to him, so I bought one for him. At around 8 bucks, why not?

This wide angle lens is a Fresnel-type, which means it's made up of lots of circular grooves cast into the surface of a rubbery material. Remember old vinyl records? Like that, but clear. The "center" of the lens is actually off-center. They have a small label on the lens to indicate the top. They did that to give the user a better view down than up. You know, to keep you from running over children and pets. The view left and right is the same. You can play around with the lens when you get it and you'll see the view to the top is less than the bottom. I think this was a good idea on their part.Installation is pretty easy. I sprayed down some water on the lens and applied it slowly. This lens doesn't have any glue. It's essentially a giant decal. The "tacky" surface will stick to glass just fine. Using water helps to get rid of trapped air bubbles, making for a clean install. I chose to use some masking tape to keep the lens from sliding while the water evaporated. I took the tape off after 24 hours, but it probably takes a few days for all the water to truly escape.Mine looks great after a few days to let all the water escape from between the lens and the rear window. One edge isn't sticking down. Perhaps the lens was a bit deformed along that edge. Not a huge deal for me, just don't expect perfection when you get this. You won't see trapped air inside the car, but they're very obvious from the outside.How does it work? It works okay, but not great. The reason i give this 4 stars is because i don't think the lens is to blame. When the lens is perpendicular to the viewer (like on a vertical rear window) it works fantastic. On my hatchback, the rear window is tilted 45 degrees or so. Given this, you get a fuzzier image and you also get some extra "Glow" in parts of the lens caused by the sun and the bright sky (see my uploaded product photos). In fact, in my case, the lower 1/3 of the lens actually showed a view up! Apparently, when you tilt a Fresnel lens enough, you can get some rather unexpected optical effects. This wasn't a huge deal, as i chose to cut off the bottom portion of the lens to make it take up less space on the back window. I mostly needed it to help me see left and right as i back up. My little hatchback has nasty blind spots (huge c-pillars) which always worry me when i back up.So, if you own a vehicle such as a van or SUV, definitely buy it. It should work awesome for you on a vertical/nearly vertical rear window. On most "typical" rear car windows (like my hatchback, tilted at 45 degrees) it will work okay, but expect some anomalies in the lens that will be a bit distracting until you get used to seeing them. If you own a vehicle with a steeply tilted rear window like or Corvette or a Prius, i'd save up to buy a rear view back-up camera instead. This lens will probably do a better job blocking the little view you have to the rear. Again, i don't fault the product here. Just laws of physics.