That is Kanger's battery, I think they call it Evod battery. I got a kit at local shop.
https://vaporbank.com/shop/index.php?p=product&id=1280
They are regulated at 3.7v, look nice and work nice. The only negatives, and they are minor, the button is pretty flush so can be hard to find by feel, also lanyards don't fit on them. I've been using mine like this for a handy stealth vape.
View attachment 218814
That's EBaron Dripper with the Protank skirt.