For around $130 you can get a REO Grand - best mod there is, no question. It has a 510/306 connector but many people use 801 adapters including myself. The batts are 18650 which last a loong time, you can always sell your 10440 batts on the classifieds..
The grand holds a 6ml
juice bottle and is made of aluminum, it's all mechanical including the switch, no wires and nothing to break. It hits like a champ every time, nothing else comes close imo.
Crappy plastic box mods will eventually need to be replaced, waste of money tbh.