The CF sub ohm has a 2000mAh LIPO cell in it.
There is no such thing as a 2000mAh 40a IMR 18650 battery.
Just be aware that should a LIPO cell vent, they vent in a violent manor.
The CF mod is the one that you an put our own IMR battery in.
Aspire CF MOD 18650 Battery for Sub-ohm