The Pulling Force of a magnet is decided by the Gauss ratings and the geometry parameters of the magnet. The higher the Gauss rating the greater the pulling force for the same size magnets. The Gauss rating is decided by the material the magnet is made of and the grade. For example, for neodymium magnets, the greater the N number, the higher the Gauss rating. So the grade N52 has a higher Gauss rating than N45, so is the pulling force for the same size magnet. At Hustle™ we use only the N52 Grade in our pedals.