Kanger has made it easier to do this by replacing the coil. All you need to do is simply unscrew the old coil and replace it with your new one.
The glass surrounding offers more safety and a healthier environment for e-liquid. The heating coil is placed at the bottom of the tank, which is a better way to heat the e-liquid and eliminates the need to constantly reverse your tank.
Overall, its a very solid setup.
NOTE: These Replacement coils are for the following:
-mini Protank II