Opteka BG-40D Battery Pack Grip/Vertical Shutter Release for Canon EOS 5D, 20D, 30D, 40D Digital SLR Camera with 2 BP-511 Batteries (4000 mAh Total) Dual shutter control for easy vertical shooting Innovative positions for shooting convenience, Tripod mountable Includes AA & Lithium Battery Trays, 1 Year warranty 2 BP-511 Ultra high power True 2000mAh, Lithium Ion 7.4v, Memory free batteries for maximum performance and extended shots - Up to 25% more Built-in safety fuse, Top graded and matched cells used exclusively