1 1/2” (37.5mm) Round Stone aka “Roofing Stone” or “Septic Stone” is a washed or dry screened clear round stone, ranging from 1” to 1 1/2”. Commonly used for ballast stone on industrial roofs, or in septic beds, this material also serves the purpose of a small Riverstone for decorative features in gardens or around the house. Due to being free of any dirt or small particles, it also makes for a great drainage stone, which can be specified for use in septic beds, infiltration galleries, and other water features.