Berkey Sight Glass Spigot provides an easy solution for viewing how much water your Berkey water filter system has left in it. The high quality Sight Glass Spigot is made to commercial specifications from machined aluminum and food grade plastics. All parts of the spigot that touch your drinking water are made of glass and food grade polypropylene #5 that is BPA free and non-leaching. Fits all stainless steel units (specify which unit you have when ordering). Makes knowing how much water to add to your Berkey stainless steel unit easier.