Just as its name, the Eleaf iJust 21700 Starter Kit is powered with a single 18650 battery. It is compatible with 18650 cell too with an adapter. It comes with an Eleaf iJust 21700 battery and an Ello Duro Tank, which adopts new HW-M2 and HW-N2 coils. The new Leakage-Proof & Self-Cleaning (LPSC) technology of two coils brings expected vaping experience to you! The four-LED indicator shows battery life precisely. This pack included a 4000mAh 21700 battery.