Tired of Lava Rock or Glass? Our new River Rock Series is another option for media over your outdoor burner. Each set comes with an 84-piece assortment of large and small stones. Large pieces ~ 4.5″ Small pieces ~ 2.5″ One set is ~ 1/2 cubic ft. (15 lbs.) (28 large stones and 56 small stones all black) These imitation stones are lightweight ceramic fiber, gel cast, and designed to take on the outdoor elements. 1 Box is suitable for up to 19-inch fire pits 2 Boxes are suitable for up to 25-inch fire pits 3 Boxes are suitable for up to 31-inch fire pits 4 Boxes are suitable for up to 37-inch fire pits 6 Boxes are suitable for up to 42-inch fire pits This River Rock set is ALL BLACK.