connected to the bottom metal ring. The two coils are both 2.2 ohms and the threaded base is a 510 thread. To fill the ProTank 2 with e-liquid, turn the body upside down and fill around the center hole. You don't want to get e-liquid down the center hole. When you have reach the desired amount, attach an atomizer coil to the threaded base and screw onto the bottom of the tank and you're ready to vape.
The ProTank 2 is a very nice tank. Compared to a basic plastic clearomizer, the ProTank 2 is high class. I love the Pyrex glass and metal parts. It has a very nice weight to it when you hold it so that alone feels like added value. I was pleased with the vapor production and although, I haven't used any of their previous products, based on the ProTank 2, I would definitely buy their future products. Kangertech has recently released the NEBOX starter Kit.