These are high-quality, rechargeable batteries from Efest that are available in a variety of different sizes and capacities.  Please ensure you are selecting the correct battery for your device before purchasing.

Efest 26650 4200mah 3.7V Flat Top.  This long-life Efest 26650 features a new, thicker purple wrap.
Suitable for devices compatible with rechargeable batteries of this size.  Electronic cigarette manufacturers have highly recommended Efest's range of high-end batteries.  They are known to be exceptionally reliable, with mass capacity for power, and have safety at the paramount point of their priorities list.