If the school's cars are made of magnetic metal (not aluminium)

Size: 30 cm

This size can be used for glass boards

so the pocket can stick together all the way around

We do not recommend this magnet for magnet fishing

Pottemagnet m. indvendigt gevind, Ø25 mm. 3M If the school's cars areThese magnets are strong neodymium magnets with M5 internal threads and have a reinforcing steel pot on the exterior. You can screw this magnet directly because of the internal threads feature. SPECIFICATIONS: Strength: approx. 14. 000 g. Diameter: 25 mm. Height: 7 mm. Magnetism: N38 Surface: nickel coated (Ni) Thread size: M5 Max. temperature: 80C This magnet has a strength capability of 14 kg. (30. 865 lbs.), which has been measured in direct pull