Material known variously as "804", 'hardcore", "crushed stone" or 'clause 804". It is a landscaping material used to create a permeable, solid base under gravel or paving. Also used for constructing paths and small roadways. Use on top of rubble or subsoil to form a solid base. Depending on how deep it is (generally approx 5cm), 1 ton covers 15 -20 square metres. After spreading, it should be compacted using a whacking plate, roller, or by vigorous stamping and firming.