That is my dome light. A lot of people put a garage opener in there. I do not have a garage so I put in a Cadillac Radar Detector made by Vogue especially for Cadillac. I just sold a new one on Ebay. It only detects the X & K bands. It is useless with the detector technology they have today but it makes for a nice conversation piece.caddyfanatic2 said:whats that thing on your picture?, With the lights.