2 years and up. Give children a smooth, solid play experience with this collection of Natural Sorting Stones. These stones are perfect open-ended play companions. Children can examine their colors, shapes, and textures use them to create a stony structure or do anything else their imagination dictates. The smooth surfaces of these stones will make children think they are getting one right out of a stream. Stones come in 3 different sizes. Largest stone is 3.25".