WindGlide (WV-BLAZ02EXT-IN Chevy Trailblazer EXT/GMC Envoy 4DOOR in-Channel Ventvisor Side Window Deflector Dark Smoke 4PCS High Quality Acrylic Plastic Material Meets or Excess OE Specification Provides UV and Scratch Resistant Install Inside of Frame To Allows Fresh Air In While Keeping Rain, Wind and Draft Out While Reduce Wind Noise. Low Profile Appearance Makes Car Wash Safe; No Drilling For Easy Installation; Tailor Made For Each Vehicle To Ensure Low Profile Stylish Look No Installation Instructions, Easily Install By Experienced Professionals; Make Sure Applied Area Are Clearly Of Grease And Dirt, Wipe Down With Isopropyl Alcohol(Rubbing) If Necessary.