The #8 limestone gravel is a very clean 3/4" stone. It has been sifted to remove the smaller stone. Because of that it works well in drainage projects because it doesn’t pack as tight and so the water can easily flow through it. Contractors often it for backfilling around house walls so the water can run down through the gravel to the footer drains instead of into your house. A lot of people use it for bases because it is 98% compacted when dumped, saving you time in not needing to go over it with a tamper or roller to pack it down.