A tank is a cartomizer surrounded by an acrylic tank. It has a long silver cartomizer, an acrylic tube, and two end caps that have rubber gaskets on either side of the tube. The cart can be completely removed from the tank so it can be cleaned.  Tanks are fully compatible with Vapor4Life's Vapor King and Vapor Titan Manual Batteries, EGO, OMG All Day, and OMG VV. Different Strokes for Different Folks There are several ways to fill cartomizers and do other tasks involved with e-cigarettes. Often there is no right or wrong way to do something. The correct directions are the ones that work best for you. It's a good idea to try a few methods and then settle on the one you are most comfortable with. Here are two different ways to fill a tank. They both work, but I prefer the second set of instructions to the first. One thing that everyone can agree on, is to always use a manual battery when refilling juice yourself. Instructions #1 1) Lay a paper towel on the surface you are using. Remove the drip tip. Push the silver cartomizer down through the bottom of the tank about 1/2 inch. You should see a small gap between the top of the tank and the clear acrylic side of the tank. 2) Tilt the tank slightly and fill directly into the cart until it overflows. Then fill the tank that surrounds the cart. Leave some room to push the cart back inside the tank. 3) Push the cart back up inside the tank. The pieces should fit very tight, so be sure the metal gaskets are flush with the tank. Wipe off any juice that may have spilled. Put a drip tip on the cartomizer and screw on a battery. You're ready to vape. 4) Refill when the juice is getting low on the outside of the cartomizer. Instructions #2 1)   Lay a paper towel on the surface you are using. Remove the drip tip and the top metal gasket. 2) Fill the tank about 3/4 full on the sides of the open tank. 3) Keeping the cart in the tank, put the drip tip on the cart. Try not to push the cart out of the tank. 4) Carefully cover the hole on the bottom of the cart with your finger. You are going to inhale lightly to prime the cart. Keep checking your cart and seeing if the cart is saturated enough but not too much. You will notice the liquid start to disappear from the side of the tank indicating it is going in the cart. Be careful not to inhale too hard as you will pull liquid into your mouth and flood the cart which causes leaking and ruins the cart. 5) Fill the tank that surrounds the cart again  3/4 or less. Push the cart back up inside the tank. Set the tank on a flat surface and replace the metal gasket and drip tip.The pieces should fit very tight, so be sure the metal gaskets are flush with the tank. 6) Inhale on the tank without your finger on the bottom of the tank so air flows through the tank and you pull any leaking liquid back up into the cart.  Wipe off any juice that may have spilled. Screw on a battery. You're ready to vape. 7) Repeat steps 1, 5, and 6 when the juice is getting low on the outside of the cartomizer. Which method do you use to fill your tank?