Another option other than the clearo's is a cartotank, as I believe you were inquiring about. These involve putting a cartomizer into a juice reservor (the tank) so that the polyfill wicking material of the cartomizer stays continuously bathed in juice. Each time you take a puff from the cartotank, more juice from the tank enters into the cartomizer to replace what is vaporized.
The cartomizer needs to have holes in it for the juice to enter from the tank. You can purchase pre-punched or laser-drilled cartos, or buy empty stainless steel cartos and punch them yourself with a carto punch tool. There is a slight learning curve to using a cartotank, but watching a good demo video should be all that is required to learn how to use one.
Both tanks and cartomizers come in two lengths, 35mm (standard) and 45mm (XL). Be sure to get the same tank/carto length for what ever you purchase.
Electronic Cigarettes 101: Tank Basics - YouTube


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