The rechargeable NITECORE 18650 Battery 3100mAH (NL188). Rechargeable with the i2, i4 chargers, or internally with the Nitecore flashlights. This is a must-have battery for our most popular Nitecore flashlights. It's the same length as two CR123 batteries and is fully rechargeable inside the P25, MH, TM series, and many more. Good for over 500 charge and discharge cycles. This is the beefed up 3100 mAH battery, providing more runtime than the 2300.