Alex K Showerhead Downstems are Aqua Lab's best-selling replacement downstem and have been a staple bong accessory in our store for many years. These glass downstems add a high-functioning percolator to any bong or water pipe. Alex K downstems fit most standard bongs, bubblers, and water pipes requiring a 14/18mm fitting. The 14/18mm showerhead downstems feature quality boro glass and several diffusion slits for added airflow and superior water filtration. Alex K replacement downstems are handblown in Arizona from a quality, American borosilicate glass.