Got my CSM table put together, all is well, except I can't figure out what this is. There's a small chain, about 12 inches long, connected to the inside bottom of the table that hangs down with a small plastic piece connected at the end. The chain had a small, square magnet attached as well. I've attached photos. Can't find anything in the manual and it's not referenced in the youtube video. Help?[attachimg=1][attachimg=2]