It is a leather wrap around some closed cell foam to slow the ice from melting and keep the barrel of the bong from getting wet from condensation. http://forum.grasscity.com/bongs-bubblers-water-pipes/1251839-tired-refilling-my-ice-bucket-so-often.html I reinstalled my bubbler as there was a screen in the headpiece that was clogging up and restricting the draw. Removed the screen and the bubbler catches any particulates. This is GREAT, I can leave the vape "on" and take a toke anytime I want, no more lighters and cleaning the screen.