This website doesn't do a good job of describing this product. It mentions "variable rate" but there are no details and the instructions on the box are not clear. This is one of those that requires 5 "clicks" to turn in on and even more clicks to "preheat" and to adjust the temp. Easier to get the $7 one that u just draw on...no complicated buttons, etc.
I bought this product for my husband and he loved it.
Depends on usage and how long you charge. Lasts 4-8 months depending on usage
Ultra Premium Variable Voltage Battery - Matte Black
Gear Variable Voltage 510 Battery (each)