Cotton has become the universal wicking material for vapes. Vapers have experimented with silica, mesh, hemp, and rayon. Until then almost universally cotton was embraced and heralded as the best.
If you are going to use rebuildables like RTAs or RDAs, this is by far one of the most important vape supplies in your arsenal. This list compiles the best cotton available right now for vapes and everything you need to know about wicking your atomizers.