Propylene glycol is used to dilute liquid nicotine for e-liquid. It is a colorless, odorless substance and does not alter the flavor of e-liquid. Being that it is water-based, it is a thin consistency and is easily absorbed by the polyfill fabric inside the cartomizer of the eCigarette. This provides that "throat hit" that smokers look for, similar to tobacco. Centwins propylene glycol has a purity of 99.8% and is preserved in HDPE white, opaque plastic bottles. This keeps the liquid fresh until it is ready to be opened and blended. We offer competitive pricing and the highest quality. All products are bottled and shipped from the U.S.A.