It's a great battery, endorsed as one of the best by Mooch. These are especially excellent in regulated mods for the best in class capacity they provide, without compromising on output too much!

More is more.

Specs:

• Nominal Capacity: 4000mAh
• Nominal Voltage: 3.6V
• Maximum Voltage: 4.2V
• Discharge Current: 30A Maximum Continuous
• Approximate Dimensions: 21.1mm x 70.4mm

Price is for 1 Battery.