Pentax D-LI7 Lithium-Ion Battery (3.7v 1800mAh) for Optio 450, 550, 555, 750Z, MX & MX4 Digital Cameras (Retail Packaging) Pentax Branded Retail Package Lithium ion chemistry free from memory effect 1800mAh power Approximately 200 shots on single charge For use with Optio MX, 450, 550, and 555 cameras