2.5" Down Stem 14/14MM . . This 2.5" down stem works with your waterpipe for premium diffusion so that your rips stay light and silky. It’s also a versatile piece, working with both 14mm male and female joints. This of course opens up the variety of pieces in your collection that can benefit from this impressive down stem attachment. It’s precision crafted from prime heat-resistant borosilicate.