This is an 18mm cooling mouthpiece that you can use dry, frozen or I even like to put a little water in and freeze it on its side! Makes a wonderful dry ice wand! This can be used by itself for the lowest possible loss from filtration for oils. So much less left in this rig versus water filtration, Even frozen. And it still cools great either way! Just grab the the 18mm adapter for your erig from my site to use it.
Another great use for this is as a mouthpiece for the stackable Hydratubes! It serves as a second level of cooling and coolness, especially when they are both sandblasted, it looks fantastic!