The V4 Stacked Kit is compatible with 21700, 20700 and 18650 batteries with adaptor (Not Included) featuring a new upgraded switch mechanism, constant contact switch which keeps your batteries arc-free and clean with a slightly recessed button to allow the mod to be put down without the risk of firing. There is a 'clicky' feel to the switch and feels incredible, combined with the 28mm diameter it adds to the overall feel in the hand of the device that is not comparable to others on the market. On top of the tube sits the Unholy V3 RDA whilst still offering the great build deck as the v2 but now features new and improved airflow, The Larger drip tips as seen on the Deathtrap 2 now comes standard with the Unholy V3 RDA.