The magnet grade of the search magnets The higher grade magnets supply stronger force, however we usually use N35 neodymium magnet on our search magnets. 2. The steel cup thickness that used on the fishing/search magnets. If this thickness does not reach the minimum thickness and cannot fully guide the magnetic lines of force generated by the neodymium magnet, the holding force will become weak 3.The steel house material of the strong search magnets.  The material of the housing is also important for magnetic strength. Mild steel (low carbon) can provide the best holding force 4.Surface conditions of salvage(search) magnets. The search magnets that have no smooth surface have a weaker holding capacity than those with a ground surface.So keep the surface of a neodymium search magnet become important 5. The contact area between search magnet and the searched object  Large contact surfaces provide sufficient holding forces, while small contact surfaces can not assure strong holding force.So holding force is proportional to the contact area of the search magnet and the searched object. Please be very careful when handling neodymium fishing/search/salvage/recovery magnets because their magnetism is very strong, which may cause injury and damage electronic equipment. Do not try to put the two neodymium fishing/search magnets together because they may break due to external forces.