This material is actually 4 in 1! The first stage should be offered around 10-11 months and the material will last your child well into toddler development. The first stage is a set of round rings that have a large centre. The large centre will help the child to be successful with their limited hand-eye coordination and wrist development. The second stage is a set of smaller, wider rings that will help the child to refine their hand-eye coordination and aid in hand development as the child learns to grasp the rings in various new ways. The third stage is a set of flat, brass rings that introduce the child to size gradation while further refining fine-motor control in the fingers. The fourth stage is a set of graded, wooden rings, similar to a traditional ring stacker, but perfectly fitted to small hands. With the small centre, hand-eye coordination is further challenged. The child also begins to learn size gradation as they create the stack from large to small. This is a wonderful material that will build your child’s independence with the hand development that occurs while playing and build their self-esteem as they master each stage.