The light is extremely difficult to install, and doesn't sit flush on the ceiling as in the picture.  Additionally, the glass cover for the bulbs screws into the large tin plate on the ceiling via grooves in the glass.  We found this to behave in 2 ways.  First, it just popped off during re-install (they do have set screws for this case).   Second, it got stuck - very stuck - & we almost broke the glass to get it off.  In fact, it was so stuck, we tweaked the mounting plate (bent the metal) because we torqued it so much.  And, good luck remembering which way it turns when it's stuck like this...  The idea of having to go through this with every light bulb change, along with it not sitting flush, was enough for us to pull it down & replace with a different light.