I keep my regular ego battery for daily use at work... Im using the 900mAh with a protank II mini becaues it fits nice in my shirt pocket, though it sticks out a bit I havent found a much shorter tank. I alsio have a 350mAh ego battery that is really short I use for descreet while out and about... one day I'll move to a mod... maybe. Right now they sufficve and the protank give great vapes with one flavor wick removed and no leaking. I also cover two of the three air holes of the protank II mini for a tighter draw and more vapor...
Just my 2cents