The ET-S BDC is a new style of bottom coil clearomizer tank featuring dual heating elements to provide twice the vapor. It is constructed entirely of metal but includes a window so that you can see your e-liquid level at all times.
Very easy to fill and replace the coils with its bottom coil design. Leaking has never been an issue with the ET-S BDC line.
They are proven to be durable and very reliable.