SmartMax allows children to explore magnetism safely. The oversized pieces are specifically designed for handling by young kids as they learn about the effects of magnetic attraction and repulsion. Older children will have fun using the pieces to construct towers and bridges. The magnets are strong enough to carry up to 60 times their weight. Basic 36 includes long bars, short bars, large 1.8" diameter metal balls and a guide to build models. 25-piece and 42-piece sets are also available.