The ET-S BVC is an upgrade version of ET BVC, it has an exterior metal sleeve surrounding the tank with two small windows that allow you to see how much liquid is left in the tank at all times.
Capacity: 3.0 ML
Compatible Coils: Aspire BVC Coils
Threading: Ego Threading
Tank Material: Glass surrounded by Metal
Air Flow: Bottom
Drip Tip Size: Proprietary