Battery Cells ⁽²⁾

These are the batteries designed for the external battery vape mods. With external batteries there are 2 things you need to pay attention to when deciding on what suits you best: mAh (Battery capacity) & Amp (How much current the battery can provide). 
Having spare battery cells is a great idea so you can use your spare batteries while the others are charging. This eliminates waiting for batteries to charge so you can have your vape available to you at all times.