Our T9 Tank is equipped with bottom dual coil (BDC) technology. It is a 3.5mL tank with 510 connection for use with any of our ECTO batteries. The T9 comes packaged with one BDC and is ready to use right out of the box. It is currently available in 7 stylish colors: Gremlin Green, Woodstock, Regal Red, Cold Steel, Passion Pink, Twilight Blue, and Ninja Black.