Phoenix Star 4 Inches Replacement Downstems with Bowl PHX583 is constructed of American Northstar glass rods with a beautiful appearance. This bong downstem set has 4 inches in length and 4 slits to diffuse the smoke for better filtration. You can use it in the glass bongs which are equipped with 4 inches downtem to connect the bowl to the main chamber. This bong bowl is a 14.4mm joint size. If your downstem is broken, you can take this bong accessory as a replacement instead of buying a new glass bong. What a cost-saving set!