This is a simple yet effective high gain pre-amp that is fully contained in a standard 1/4" switching endpin jack. The gain is fixed at 25db and operates on a standard 9 volt battery (not included). The preamp turns on automatically when a cable is inserted into the endpin jack. Can be used with most passive pickups and all Pick-up The World pickups, including the SBT and UST pickups. Includes battery holder.