For those who want to maximize the filtration and smoke diffusion of their water pipe, our 18mm Downstream is a necessary addition. This downstream is designed to fit snugly and offer a smooth, bubbly smoking experience. It is compatible with any 18mm female joint. Its precisely cut slits produce tiny bubbles that increase the smoke's surface area and improve cooling and filtering. Made of sturdy glass, it's the ideal addition to your collection of smoking accessories for a smoother, purer hit.