The EHPro 454 Big Block RDA is a solid atomizer that can house up to 4 coils! It features a unique washer which is held down by the ground screws. Negative leads can be wrapped around each screw, or tucked underneath the washer to give you more build options. The Big Block also has adjustable airflow and 4 huge airflow holes for massive clounds. The top cap has 3 parts the heat sync, the center which attaches to the deck, and the outer ring. After lining up the airflow holes in the center piece, rotating the outer ring will allow you to adjust your airflow. With a copper positive contact to round it out, the EHPro 454 Big Block is a hunk of hardware that will live up to any vaper's expectations!