The EMOW tank is dual bottom coil design. It is easy to refill and performs great. This kit features replaceable coils, so you can use the tank indefinitely and replace only the coils. The EMOW battery is a top of the line variable voltage ego battery, It has three voltage settings: 3.7, 4.2, and 4.8 volts. It will hit hard throughout the discharge cycle of the battery. The battery will provide you with the same great power from the start of your day until the very end.