Phoenix Star 4 /4.5 / 5 Inches Downstems with Matrix Perc PHX555 is constructed of high quality Boros glass. The glass downstem PHX555 has three lengths: 4 inches, 4.5 inches and 5 inches for options. You can put a 14.4mm glass bowl into this downstem to use. The bong downstem PHX555 connect with the main chamber of an 18.8mm glass bong. This glass downstem is equipped with Matrix perc to diffuse smoke to create more bubbles and more interact surface with water. The better filtration, the smoother flavor you and your customer can enjoy. And you can watch the bubbling water via transparent glass to be relaxed.