You guys are right. I recognized it too. I seen a few of these degausers. Todays monitors can degaus on thier own. TV's can't. It's just an electro-magnet used to relighn the electron guns. The glass on CRTs (or maybe the phosphors on the glass) build up a magnegtic charge. You see this as a change of color usually in the corners. Maybe a blue tint, red tint, etc. The degauser is used to remove the residual magnetic charge.
I guess that's more than what was asked for. I felt cheap just saying that I agree with what was already said.
*edit* Too many spelling errors to correct. Sorry.