South Cerney gravel is quite good, it's rounded so feels comfortable, but the pieces are flattened and irregular so it's more stable than pea gravel. It's an unobtrusive buff colour. 20mm slate stays in place the best and is the most comfortable, but the dark look isn't for everyone. It's the best for laying on existing concrete because it lays flat.
"What is hateful to you, do not do to your neighbour".
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