The 
Nuprol Power LI-ION 1500mAh 20C "Double Stick" battery
 is a compact, high-efficiency power solution primarily for airsoft guns, known for its long lifespan and lack of memory effect. It is also referred to as a "nunchuck" style battery due to its split-cell configuration.
 
The battery is available in two voltage variants: 7.4V and 11.1V, both with the same capacity and discharge rate. 
Specification 
Details
Battery Type
Lithium Ion (Li-Ion)
Capacity
1500mAh
Voltage Options
7.4V or 11.1V
Discharge Rate
20C (Continuous) / 40C (Burst)
Configuration
"Double Stick" or "Nunchuck" (split-cell design)
Connectors
Available with Mini Tamiya or Deans (T-Connector)
Recommended Use
Airsoft Guns (AEGs), RC models, drones, UAVs
Charging
Requires a specific Li-Ion Balance Charger and should be charged in a fire-retardant safety bag