VERY RARE, Serial number 403 Crown DC 300 Power Amplifier constant voltage PA adapter. For it's age, in very good shape (see pics). If you have the amplifier and want to complete the set, this is a once in a lifetime opportunity. Retired sound guy, selling off some gear. Page 8 of manual has complete description - see attached. Load here: https://www.google.com/search?q=crown+dc+300+manual&ie=utf-8&oe=utf-8