Guidecraft Better Builders 30 - Piece Magnetic Ball and Rod Construction Set, STEM Educational Building Toy Open-ended magnetic construction toy for preschool age children Set includes 30 primary color pieces, storage bin and an activity guide Over-sized rod shapes with grooved grips and inset magnets are perfect for small hands Coordinates with all Better Builders building sets Educational Focus: Exercises creativity and based on STEM principles including science, engineering and magnetism