VSR Pro 4™ Traction Magnets are a ceramic grade compression molded polymer magnet. The Pro 4™ magnets are made to replace brittle and expensive Ceramic magnets. All magnets have readings that are consistent with the highest grade ceramic magnets available. This means no searching through hundreds of magnets for the best ones. All magnet batches are precisely controlled and consistent. These are designed to fit the Viper V1 chassis.