I haven't noticed it keeping spray off the back window, it might help since there is an upward curve but I doubt it. I don't get much on my back window since I keep it clayed and clean along with the other glass, and sealed with Rain-X or similar, even with the rear wiper delete I notice no ill effects but thats for another thread.

It's purely for looks, does not generate any noise, just looks nice. I bought mine pre-painted for $90 (actually my wife got it for Christmas for me), color match and quality was dead on and shipped from Taiwan in 10 days.

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards