The 2-ply gaskets are made to fit over modern stem hub theads on most modern hookahs. Recently, many modern Chinese hookahs have been made with threaded hubs and in order for the stems to fit on a standard (non-threaded) bottle, the thin side is placed over the threaded portion to make for an even fit. Coincidentally, these work well on almost any hookah including Egyptian hookahs. When the thicker portion of the gasket is put toward the top of the hub, it makes a seal that gets much stronger as the vase is pulled up over the stem. The end result is a flush look and tight fit.
