BigOtters painting rocks are just perfect for my project~ It's a bag of 20 grey color river rocks. Each one is about 2.5" in size. They are pretty clean and can be used immediately if wanted to. I like the way each rock is almost the same size and I can hold it in my hand to work on it. Smooth surface and No sharp edges, Muliti use for these river rocks besides to paint them. They can be used to decorate palnters, decorating fish tanks. It's a lof of fun painting on these rocks~ very satisfying~