Olympus SHLD-2, Power Battery Holder Set with Battery Pack, Batteries & Charger.

HLD-2 Power Battery Holder.... Experience all the performance that the E-1 has at full capacity. The high-powered external battery power grip conveniently and easily attaches to the base of the camera while supplying an extensive power supply so you can shoot a day-long assignment without hesitation.

More than just extra power, the HLD-2 also improves the focus tracking speeds in Continuous AF, allowing you to track faster moving objects. When attached, the HLD-2 also includes a space to store the E-1's body battery cover door so it is not lost or a hindrance to carry.