There are two main options. You can fill Top-fill tanks by opening them at the top. You just need to unscrew the top part. If it has a slide-open mechanism, you can simply push it open. Bottom-fill tanks usually require that you remove them from your mod and unscrew the base.
How do I choose a tank?
Putting look aside, we you can offer you the following tips
510 or eGo connection
First of all, the tank needs to have the same connection of your battery or mod (i.e., 510 or eGo). Make sure you check the specifications of the mod and tank. 510 is by far the most common connection.
Single or dual coil
The number of coils contributes to determine the amount of vapor. The difference between single and dual coils is particularly relevant for Rebuildable tanks, because the resistance created by two coils is half of the value of each coil. So, if you like a somewhat higher resistance (i.e., lower wattage), a single coil tank is your best option.
Mouth-to-Lung (MTL) or Direct Lung (DL) vaping
You need a different tank depending on whether you inhale straight into your lungs (DL) or if you first hold the vapour in your mouth (MTL). Direct Lung tanks tend to have more open air flow and wider drip-tips. The coil resistance tends to be lower.
Is there anything else I need to know?
You can get more information on the relevant sub-sections. If you have any questions, do not hesitate to contact us.