Gravel is available in 10mm or 20mm. 10mm being used for decorative purposes such in a garden patio or a surround for a landscaped area. It can also be used for drainage purposes when wrapped in membrane, making a permenant space for water to sit in, preventing the ground from becoming waterlogged. 20mm gravel is used for areas with high loads such as driveways and carports. There are enormous varieties of colours and shapes of gravel, something for everyone. For a range click here.