A sub-ohm tank is a tank that uses coils with a resistance lower than one ohm. For instance an example of a sub ohm tank is the Aspire Cleito. Their are two different coils available for the Aspire Cleito that are of the same design as one other but have different resistance ratings (0.4ohm and 0.2ohm).
Sub ohm tanks, also known as sub tanks are typically direct to lung tanks. This means that you the user inhale the vapor from the tank directly to your lungs in one fluid motion instead of inhaling the vapor first into your mouth and then into your lungs in two separate motions. If you’re unsure of the difference between mouth to lung vaping and direct to lung vaping why not check out our informational section on types of vaping.