NiteCore RCR123 re-chargable battery
NiteCore RCR123A Li-ion Rechargeable Battery
- 650mAh 3.7V 2.4Wh
Integrated battery overcharge / discharge protection circuits
High discharge performance Li-ion Rechargeable Battery
Similar dimensions to standard CR123 batteries. However, note that the voltage is probably slightly higher. Check with your device manufacture for compatibility.
Two RCR123A batteries in series (end to end) may be used in place of an 18650 (they will offer same output voltage as an 18650 and will have similar physical dimensions.