All Fenix rechargeable Li-ion batteries is a high capacity cells with a protection circuit in the anode
to help prevent short circuits, over charge/discharge and overheating.

The batteries also includes pressure relief vents which expel waste gas in the rare case of an internal short circuit preventing an explosion.

Characteristics

• Designed with a protruding contact point for series use
• Has no memory effect
• Negligible self discharge
• Outstanding performance
• Excellent reliability
• Compact design
• Is the best match for your high-drain devices such us Flashlights
• More than 500 cycles
• Light weight

Further Info : 

• Li-ion batteries should never be left charging unattended under any circumstances. 
• The user must have knowledge of how to charge and discharge Li-ion batteries before using them. 
• Always use a charger that is designed to recharge the particular Li-ion cell that you wish to recharge. 
• Never use a DC adapter to charge Li-ion batteries. 
• We are NOT responsible for any damage that is caused by the misuse of Li-ion batteries. 
• We recommend charging any Li-ion cell on a metal or other non-flammable surface.