Description: The reciprocating electromagnet used in this product is a better magnet obtained after many experiments, replacements and calculations. It is with the Hall sensor to generate magnetic force at a good position, so that the running effect is better. The bearings are ball bearings, featuring: low friction, quiet and durable, providing strong support for smoother operation. Acrylic bracket support with high-precision cutting on both sides, featuring high transparency, no deformation, and beautiful appearance The beam bracket is a four-carbon fiber column that is durable and stable. Perfect for children& 39;s science projects, physical/mechanical learning, teacher presentations in the classroom, birthday gifts for friends, family, parents, children, etc. Specification: Material: ABS Plastic Size 4 Coils: 230 x 108 x 110mm / 9.06 x 4.25 x 4.33inch 8 Coils: 280 x 108 x 110mm / 11.02 x 4.25 x 4.33inch 12 Coils: 330 x 108 x 110mm / 12.99 x 4.25 x 4.33inch Package Includes: 1pc Model Engine Kit