DCT stands for Dual Coil Tank. Each tank has a dual coil cartomizer that goes up through the center. The cartomizers have 2 or 3 small holes drilled in it to all the juice in the tank to feed through and keep the polyfill wet. These are a useful option of variable voltage vaporizors. The polyfill holds the juice clost to the coil making them extremely resistant to high voltage/wattage. The combination of the cartomizer and tank hold approximately 3.5 mL of juice.