The Fenix ARB-L18-3500 is a high capacity 18650 Li-ion rechargeable with a protection circuit in the anode to help prevent short circuits, over charge/discharge and over heating.  The battery also includes pressure relief vents which expel waste gas in the rare case of an internal short circuit preventing an explosion.

Features:

• ARB-L18-3500 Rechargeable Battery
• 3500mAh high capacity
• Protection circuitry to prevent short circuits
• Pressure vents to prevent explosions
• 500 charge cycles

Voltage: 3.6V
Charging Current: Recommended 1A, maximum 2A
Weight: 1.8 ounces (50g)
Size: Length: 2.7″ (69mm) Diameter: 0.7″ (18.6mm)
Warranty Period: 12 month from date of purchase