The Eleaf iJust 21700 is the "next generation" sibling of the wildly popular iJust 3. What makes this kit a useful upgrade from the iJust 3 is it's user-replaceable battery feature!  You can install a high capacity 21700 battery, or use a standard 18650 high-drain battery with the included adapter.  Rock Bottom Vapes offers this kit both with and without a 4000 mAh - 21700 battery direct from the factory.  So, if you already have a 21700 cell or want to use your existing 18650 cells you can save a few bucks and order the kit without a battery.
Like its sibling, this simple to use tube style device can support up to 80W of output.  This device is not just any run of the mill tube-style mod though, as it boasts a beautiful laser-etched design in five vibrant finishes.  Included with the iJust 21700 is the equally gorgeous and powerful ELLO Duro tank. The Duro tank which ships with this kit has a gorgeous color-matched acrylic tank.  This tank uses the latest Mesh (HW-N2) and Multihole (HW-M2) coil systems which provide more uniform heating of the wick.  What does this mean for you?  In a word - FLAVOR. The ELLO Duro has a 5.5mL maximum e-liquid capacity (depending on the tube installed), and features a retractable top-fill design and rotatable dual bottom airflow ports.