This is just standard tan pea gravel you can buy in bulk from a stone or landscape supplier, or by the bag at home depot for small projects. The best way to install a driveway like this is a very thin layer of gravel over a substrate of chert or similar subsurface. The substrate keeps the thin layer of gravel from moving about. The worst way is to dump a 4" layer that you can barely drive over and which winds up in the street.