This is the 1000mAh Aro Winder Variable Voltage Battery from Smok Tech.
The Winder improves upon the design of the twist batteries while still retaining the simplicity of the twist's design.
Clearly marked voltage setting that you will not need a magnifying glass to see.
1000mAh battery capacity for a day and a half or two days of use without charging.
3.3v to 4.8v smooth turning voltage adjustment dial.
5 click button lock.
Works with 510 and EGO gear