The G6 tank has a 4 ml capacity. The tanks use a cool system similar to the Triton tank system. If you want a vaping experience using a tank as similar to the Triton tank system. Try the g6 mini tanks. Easily attaches to the G6 battery, easy to see how much e liquid placed inside the tank. Using cartomizer and tanks is a great way to vary your vaping experience. The best of both worlds. Still small enough to carry in pocket or clutch and colors match your G6 battery.