The Mutation X V4 is the fourth generation Mutation X by Indulgence. Indulgence is a subsidiary of Unicig. This is not a clone. This authentic RDA has an innovative design. It features serrated edges to adjust the airflow holes like the V3. Version 4 includes airflow routed underneath the coils and through the barrel. These are all adjustable. A redesigned top cap and drip tip are also new features!