This is a freezable glycerin attachment from Cheech Glass that sits between your bowl and your bong. The sealed glycerin coil can be chilled in the freezer, then it cools the smoke as it passes through for a much colder, smoother hit, while the coil percolator adds an extra round of diffusion. It fits 14mm female water pipes and comes in cool colours. It's built in borosilicate glass. A worthwhile add-on for someone who wants the coldest possible hits without putting ice in the main piece.