The GuitarHeads Active Humbucker features an Internal Preamp that is designed to increase sustain, add depth, and enhance overall response sensitivity. The Preamp is built right into the pickup's casing, which is Epoxy Potted for the ultimate suppression of microphonic feedback. The result is an Extreme Output, and plenty of bite due to the Anisotropic Ferrite Magnet (a High-end Ceramic). A standard 9v Battery will power a complete pickup system (up to 3 pickups), and will last over 2000 playing hours. Mounting Screws & Height Adjustment Springs are included.