This Coil unit is the replacement part for Protank3, AeroTank and EVOD 2 Clearomizer. It can not work with other protank or unitank.
How to replace the coil unit/coil head? Turn upside down the cartomizer, then screw off the bottom base. Take out the old coil unit from the bottom base, replace with new one. So easy!
Please be sure that the coil unit is screwed into the cartomizer tightly. If you get few vapor when you use, try to make the clear cartomizer upside down to let the fibre wick and coil get e-liquid, which are on the top of the cartomizer.