Visit Amazon sites : br Fotodiox Pro Turbopack 9000 - DC 12v 25Wh Power Pack for B4 23 Lens (Fujinon Nikon Canon Angenieuxbr br Provides power to the Zoom Servo Functions including Quick Zoom Cruise Zoom Memory Functions br Switchable DC Output to suit your lens needs 12v 16v or 19v br Battery does not have a sleep function so the lens will always be ready to go at a moments notice br Built-in power indicator lets you know when the battery needs a recharge br 24 Month Manufacturer Warranty