IMR batteries are some of the most popular batteries for electronic cigarettes. Depending on how much you vape, you could need to swap a new battery in every couple of hours to get the best hit. Most people have a few extra e cig batteries on hand to make sure they have one ready when they need it.
The most common IMR battery is...
Model: IMR 21700 Rated Capacity: 3700mAh
AWT 18650, 40A, 2600mAh Battery
Flat top 3.7 Volt 18mm diameter, 49mm height