Most stacking toys I've seen have been fairly simplistic: The objects stack, they might nest, but that's about it. This product consists of ten well-engineered plastic hemispheres that snap together in a variety of ways, numbered 1 to 10, plus a metallic jingle ball head. The pieces stack or nest, as they should. Because of their shape and molded grooves, any two bowls will snap together; for instance, any of the 7, 8, 9 and 10 pieces will snap onto the 6 piece. Pieces are designed to snap together firmly enough to hold together, but lightly enough for an infant to pull them apart; for the most part, the reality lives up to the design, erring to the side of being too easy in some cases to pull apart. In addition, because they're hemispheres, any two consecutive pieces will snap together to form a ball. This allows you to create up to five balls of increasing size; it also allows for easy storage, because all of the balls (including the head) nest together. And of course, the bright pastel colors hold an infant's interest. My son enjoys banging the pieces together and knocking over my constructions. The hemispheres also have a flat spot at the end for stacking pieces end-to-end, but that tends to be unstable. The one improvement I would suggest is that some sort of grooving be added to the flat spots to allow better end-to-end stacking. However, there are so many other ways to play with these that this drawback is only a minor one.