These are replacements for the E-Liquid capsule of the Suorin Air Starter Kit. The cartridges are refillable and hold up to 2ml of E-Liquid. Simply remove the plug from, and then pour down into the filling hole to keep your E-Liquid level topped off. Make sure to keep the metal connection points clean so your Suorin Air mod can fire properly on the cartridge. There is a cotton wick that pulls the E-Liquid from the liquid chamber to the atomizer to be vaporized.