Have fun building incredible structures with SmartMax! 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, while older children will have fun using the pieces to construct towers, bridges and other creations. They magnets are strong enough to carry up to 60 times their weight! The Start XL set includes 18 short magnetic bars, 12 long magnetic bars, 12 magnetic balls and a guide to build models. Extension sets are available separately.