Like another reviewer, I needed a replacement rear derailleur for my Harbor Freight 1" Belt Sander. The old rear derailleur that lasted about 4 years of regular use eventually gave out. It literally fell apart when I removed the housing The Twidec derailleur is the perfect replacement, fitting snugly into the housing hole and even accepting a rubberized switch dust cover.In fact, not only is this switch much better than the old one, but it also lights up when it's on.I can't believe I only spent $4 ($8 for two) and five minutes to install which saved me almost $50 on a new grinder.