Practical Design Our magnets hook are made of high-grade Nd-Fe-B materials. Neodymium magnets are the strongest type of permanent magnet currently made.They are amazingly powerful for their size and have innumerable uses.Data based on scientific measurement Pulling Force: 25 lbsAfter many measurements, we have obtained scientific and rigorous measurements by pulling the hook at a uniform speed on professional equipment.Several Important Factors Affecting the Tensile Force of Magnets1.Only when the thickness of the tested steel reaches a certain level, the magnetic flux through its cross section would be the largest and the leakage magnetic field between the magnetic poles is the smallest, the tensile energy can reach the ideal value.2.Only when the force is perpendicular to the contact surface can the tension reach the maximum. When the force is parallel to the contact surface, the pulling force can only reach 1/3 maximum.3.Magnets attract only magnetizable materials such as iron, cobalt, nickel and their alloys. It can not attract non-ferromagnetic plates such as aluminum, copper, wood, plastics and stainless steel.4.The farther the magnet is from the magnetic material, the greater the leakage magnetic field and the smaller the pull force would be. Therefore, the surface paint adsorbed by magnets is also animportant factor affecting the pulling force of magnets.WARNING1.Keep away from pacemakers.2.Powerful magnets can hurt your fingers.3.Not for children, parental supervision required.4.Please wear a pair of gloves when you handle them for your safety.5.All magnets may chip and shatter, but if used correctly can last a lifetime.6.The maximum working temperature of neodymium iron boron magnetic is 176 F (80 C)