A collector's item! This copy was purchased in 1979. Original receipts and boxes included.  Virtually no signs of wear! The Musitronics Mu-Tron III was manufactured between 1972 and 1978.  According to reviews, this is the best  "Envelope Filter" ever created. Its "legendary" effect can be heard in the song "Higher Ground" by Stevie Wonder. 
 
*Comes with the "PS-1" transformer in immaculate condition! Originally sold separately, this piece is now virtually UNFOUND!