It is a plate or cover that covers a sensor (rain or rear view mirror light detection?) that is on the windshield, directly behind the rear view mirror. Here's a couple pics of it. I have a 2004 XC 90.

The snaps are broken and it will not stay in place. I would like to order a new one? Can I do that online?

 

best way to order online is to go to one of the dealer parts web sites. NAPA's not going to carry such a part. Start with tascaparts.com and if you don't see it then google around for other dealer parts stores. The other option is to go to a local dealer, ask them to research the price and part number, write it down, then google.

 

Sir, thank you. I have actually done that but you need to know what the part is before you can get the part number. It's kind of a Catch 22.

 

It's tedious but you need to search the diagrams