Discover the secrets of Earth’s magnetic field and learn how the compass works with Geomag Mechanics Build Your Own Compass. The set contains 21 pieces. Age 5 years – adult. Warning: Contains small parts that may be swallowed and spheres that may represent a chocking hazard. Not suitable for children under 3 years. Contains strong magnets. Keep away from sensitive devices such as credit cards, computers, magnetic media and medical devices (pacemakers).