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Quarter Window Louvers (15-20 Fastback)

Item 394120
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Market Price $229.97 You Save 5% ($11.50)
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$218.47 (pair)

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      Review & Installation Video

      Hey guys, today we're gonna be taking a look at and installing the Defenderworx quarter window louvers, for all 2015 to 2018 Mustangs. These are an unpainted polyurethane quarter window louver with a matte black finish. They cost about $200 and you can see they have a very stepped louvered design. They give you a little bit of a different look than some of the other options on the website. Like any other exterior mod, these are all about personal styling. You can install them right out of the box with the matte black finish or they're also very easily paintable, so you guys can paint them if you want to. They're easy to install, I'll call it a one out of three wrenches in the difficulty meter and I'll show you how we got them on the car now. All right guys, so the first step of our install is actually gonna be to flip the louver over. We're gonna apply some adhesive promoter to the flat edge all the way around the louver here and then we're going to apply the 3M tape. So I have a pair of scissors here so I can cut the tape when I need to. We're gonna go ahead right now and get the promoter on the louver before we apply the 3M tape. So we're just gonna apply the 3M tape on the flat surface of the louver here. We're gonna leave the backing on it for now. All right so we do wanna make sure that none of this 3M tape hangs over the edge of the louver because you will be able to see it. All right, I'm just gonna fill in this space right here with a smaller piece of tape just because I do wanna make sure I get as much 3M on here as possible. So with the 3M on the back of the louver, we're actually gonna flip it over now. And once again these are very lightweight and they do come with this matte black finish. They're very easily paintable, so you guys can paint match these if you want to or you can install them right out of the box with a matte black finish like we're gonna do today. So you do get two stickers from the Defenderworx. They're right here and I will say that if you're gonna paint match yours and you wanna put the stickers on, make sure you do it after they're painted. We're gonna go ahead and just stick one of these stickers up in the corner right now before we get this on the car. So at this point we're actually gonna test fit the louver before we peel the backing off the 3M tape just so we're really familiar with where it's gonna go and how it's gonna sit on the window before we go to actually install it. Another thing to say here is that you're gonna wanna make sure your window is as clean as possible. So you're gonna want to use an alcohol prep pad or anything that'll cut through any grease or wax that could be on the window. We've already gone ahead and cleaned our window. One other thing to point out is this is a louver design, so you guys can see that you will be able to see or have some light come through this louver on the new rear quarter window here. If you guys don't wanna see the unfinished backing of your louver or you don't want that light coming through, make sure you pick up a quarter panel blackout decal and install that prior to installing your louver. So we're gonna go ahead, test fit this on the car and just get a really good idea where it's gonna be. So before we go ahead and get the louver installed, we're gonna use 3M adhesion promoter on the window as well. We're only gonna be putting it where the 3M tape is gonna sit. We're gonna go ahead, just make a line around our window. Now we're gonna peel the backing off the 3M tape. Now we'll just press this into place. Gonna want to make sure that you are perfectly lined up because with the adhesion promoter on the glass the 3M tape's gonna stick right away. So now I'm just gonna go around the entire louver and make sure it's pushed into place. One of the nice things about these louvers is they apply to the glass so they're gonna leave your quarter window trim exposed. All right guys, that's gonna wrap up this review and install. Keep in mind you can always check these out more online right here at

      Product Information

      Features, Description, Reviews, Q&A, Specs & Installation


      • Aggressive Styling
      • Louvered Design
      • Polyurethane Construction
      • Matte Black Finish
      • Simple Peel and Stick Installation
      • Driver and Passenger Side Louvers Included
      • 4-Year Limited Warranty
      • Fits all 2015-2020 Ford Mustang Fastback Models


      Aggressive Modern Design. Make your Mustang stand out at your next car show with a set of Defenderworx Quarter Window Louvers. These stepped Louvers were designed to give your fastback S550 Mustang a more aggressive muscle car appearance. With these Quarter Window Louvers on your Pony, you are guaranteed to turn heads wherever you go.

      Polyurethane Construction. DefenderWorx manufactures their quarter window louvers from industrial-grade, OEM quality injected molded polyurethane for superior strength and long lasting durability. These Louvers are completed in a matte black finish that allows them to be installed straight out of the box.

      Easy Installation. No fuss, no muss installation. DefenderWorx Quarter Window Louvers are designed to attach to the factory C-Pillar glass with the supplied 3M doubled sided automotive bonding tape for a quick and easy installation. Just clean the surface, peel the backing and stick in place - it's that easy.

      Recommended Styling Upgrade. When installing exterior quarter window louvers or scoops on your Mustang it is recommended to add a set of quarter window blackout decals to hide the ugly back side that wasn't meant to be seen by human eyes. See option above.

      4-Year Warranty. DefenderWorx guarantees to the original purchaser of its products a 4-year, 36,000 mile warranty, against manufacturer defects in materials and workmanship under normal use. Some exclusions may apply, please see manufacturer's warranty for details.

      Application. Defenderworx Quarter Window Louvers are designed to fit all 2015 to 2020 Fastback Mustangs, including the V6, EcoBoost, GT, GT350 and GT500 models. Sold as a set of two, one driver side and one passenger side.

      Fitment: 2015 2016 2017 2018 2019 2020 Details

      MPN# 901448

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (20)

      Write a Review

      Ratings Summary

      4.6 out of 5 overall rating from 20 customers

      Installation Time: Less than 1 Hour

      • January 05, 2020

        5 2019 Bullitt - ShawnA Installation Time: Less than 1 Hour


        I have no complaints about the product I purchased! They shipped in a timely manner and I had them painted right away so I could put them on the Mustang! I will continue to shop with American Muscle!

        Helpful (0)
      • August 28, 2019

        5 2018 GT - Omgshweet1 Installation Time: Less than 1 Hour


        Install was easy and quick, they look great and they are high quality.

        Helpful (1)
      • June 03, 2019

        4 2019 Bullitt - JohnF

        2019 Bullitt

        Overall I was impressed with the look and quality of these louvers. I'd rate them five stars if not for a minor fitment issue on the front bottom edge which might be specific to the Bullitt due to the chrome window reveal molding. (I had to lightly sand about 1/16" off from the bottom front edge back about 2 1/2" to get the louver to lay flat against the glass without binding.) Be aware that these louvers are designed to be painted. I sprayed them with a flexible/sandable primer surfacer followed by acrylic urethane, three coats of base four coats clear, then color sand hand buff. It takes a little time to do it right but it's worth it.

        Helpful (1)
      • April 04, 2019

        5 2017 EcoBoost - Nicolai614 Installation Time: Less than 1 Hour

        Adds a nice, aggressive look.

        I was looking at multiple different styles of louvres and finally settled on these. I’m glad I did. Material is nice and install is simple. Complete install took about 15-20mins. Couldn’t be happier with the purchase.

        Helpful (0)
      • March 16, 2019

        3 2019 GT - DP Installation Time: Less than 1 Hour

        Defenderworx louvers

        The design is great and I like the idea you can see between the vents. I was not too happy on the out of the box flat finish. They look like they need painting. Sturdy construction, not too flimsy. All in all they look radical on my 5.0. For a price of over $200.00 they could have a least put a nice coat of flat black on them.

        Helpful (0)
      • January 27, 2019

        5 2017 GT - JeremyL Installation Time: Less than 1 Hour


        It fit perfect and looks great love it. It came in like they said in 3 days. That's why I sway use American muscle.

        Helpful (2)
      • January 02, 2019

        5 2018 GT - LorrayneP Installation Time: Less than 1 Hour

        Quarter Window Louvres

        I just installed these louvres last night and they fit perfectly! I ordered the matte black and they look great with the matte black trim. Installation was quick and easy. This is the second set of Defenderworx louvres I’ve purchased and it’s a great product.

        Helpful (2)
      • November 06, 2018

        5 2017 EcoBoost - TomL Installation Time: Less than 1 Hour

        Love the Louvers

        Good product, well constructed and looks great and I can still see out the side windows. Easy to install as long as you make sure your tape is positioned properly.

        Helpful (2)
      • July 28, 2018

        5 2015 GT - Frank Installation Time: Less than 1 Hour

        Yeah Baby

        The looks say it all. I was able to install the louvers in no time flat, 15 minuets for each side.

        Helpful (2)
      • July 01, 2018

        5 2017 GT - WilliamV Installation Time: Less than 1 Hour

        Love these Louvers

        Good product, good fit, and overall appearance is awesome at completion of the install.

        Helpful (2)

      Questions & Answers (4 answers)

      4 Top Rated Questions

      Are there drain holes to handle car washing and rain water?

      • Water will drain naturally, due to the shape/angle of the louvers.

      Helpful (1)

      How much visibility do you have from the inside?

      • This Defenderworx Quarter Window Louvers will still allow some visibility, however, it will only be in the amount of the open space in the louver slots.

      Helpful (1)

      I'm Looking for a textured ABS style quarter window louver to match the MMD rear window louver. Do these have a little bit of a textured surface like the factory exterior black plastic trim pieces on the car or are these a smooth surface? Thanks-!

      Are these louvers paintable?

      • The Defenderworx Quarter Window Louvers are able to be painted, however prep, sanding, and primer will be required.

      Helpful (0)
      Post Your Question

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Pair Quarter Window Louvers

      Tech Specs

      Will It Fit My Mustang

      • Bullitt - 19, 20
      • EcoBoost - 15, 16, 17, 18, 19, 20
      • GT - 15, 16, 17, 18, 19, 20
      • GT350 - 15, 16, 17, 18, 19, 20
      • GT350R - 15, 16, 17, 18, 19, 20
      • GT500 - 20
      • V6 - 15, 16, 17

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