Every bottle of e-liquid typically contains four primary components: Propylene Glycol (PG), Vegetable Glycerin (VG), flavorings, and optional nicotine. The ratio of PG to VG is the most critical factor for device compatibility:

Thinner liquid that provides a stronger "throat hit" similar to traditional smoking. It is ideal for low-wattage starter kits or pod systems.

Thicker liquid that produces large vapor clouds and a smoother inhale. It is best suited for high-wattage sub-ohm devices .