An oil tank is super similar to an oil pod, the only difference lies in its size and actual usage. An oil tank is used with vape mods, as they are larger and require a bigger coil as compared to the small coil found in a pod. To make a long story short, use an oil pod for your vape pen, and use a oil tank for your vape mod.
eSmokeShop has a good selection of different oil tanks for all your vaping needs! Most of them come in different shapes, sizes and colors for your own personal unique customization!