The Canon LP-E4n Rechargeable Lithium-ion Battery.
The Canon LP-E4n Rechargeable Lithium-ion Battery, has a capacity of 2450 mAh, so it is possible to shoot up to 2300 shots at normal temperatures on a single battery charge. The battery is also lighter in weight than previous battery models.
The LP-E4n Battery also communicates with the EOS-1D X, so that you can always check the remaining capacity (marks in six levels and percentage in 1% increments), shutter count and recharge performance on the camera's power source info screen.
Output Voltage: 11.1v
Canon LP-E4n Li-Ion Battery Pack for 1DX