A Mod usually used to describe a design variation on a commonly mass produced e-cigarette. These mods could for example, use larger rechargeable Lithium Ion batteries for longer battery life and/or increased voltage. These devices can be shaped like anything, a cigarette box, or a sonic screwdriver, or, like anything. They no longer look like a traditional cigarette. Some mods will also allow you to vary the voltage and/or wattage (VV/VW) of the device to achieve optimal performance.