The holes are for screws...I also just used the glue that came with them. On the windshield surround I would not recommend (IMHO) using any extra adhesive. If ever you should have to replace your windshield, and the OEM window surround gets damaged and your chrome one gets damaged also because it is permanently attached you now have a problem. I actually purchased "3M Automotive Tape" and just added some more tape for insurance. Now if ever I have to have my windshield replaced I can remove the chrome surround and then the OEM surround.