The Focus V Replacement Batteries give you the basic life force of the Focus V Carta Vape Rig. With these batteries, you can use your Carta Vape Rig anywhere, so it pays to carry an extra pack on you at all times. If one set gets depleted, switch out while your other batteries charge, and you can keep using your Carta indefinitely. These batteries helped put the Focus V Carta on the map. Now you can have an extra set of 2 to keep you going!