High-capacity Battery Pack BP-511A (rechargeable lithium-ion battery) for EOS digital SLR and Powershot G models as well as select Canon camcorders.
Compatible with:

Canon Digital SLR:
EOS 20D, 10D, 30D, 40D, 50D and the 5D ( not suitable for the 5d MK II)

Canon PowerShot:
Pro90 IS, Pro 1, G1, G2, G3, G5, G6

Canon Camcorders:
Optura Pi, ZR10, ZR20mc, ZR25mc, ZR30mc, ZR40, ZR45mc, ZR50mc

When used with camcorders, the BP-511A gives you a maximum recording time of 2 1/2 hours using the viewfinder, or 2 hours using the LCD screen.

When used with the EOS D-series cameras, the battery is capable of approximately 300 shots on a single charge.

Use with CB-5L battery charger, sold separately.