HYDRO Vapor Stones are non-tobacco porous rocks that have been injected with glycerin and other flavorful fluids that when heated with charcoal, produce steam rather than smoke. This method of hookah smoking is ideal for those that prefer tobacco-free alternatives. For the best results with Hydro Hookah Vapor Steam Stones, we suggest using a phunnel bowl or a vortex bowl. Both types of bowls allow the juices from dripping into the hookah from the bottom of the bowl and provide a thick, flavorful smoke.