Magnetic holders are parts that can hold objects in place using magnetism. Besides holding objects, they are also used for transportation purposes. The right amount of magnetic force for the magnet is usually selected by considering the material and shape of the transported object. Other factors to consider include the impact during transport and the amount of bend when the object is raised. The magnets are made of materials such as alnico, ferrite, samarium and cobalt rare earth elements. Powerful holding forces can be adjusted by applying thin plates to the holding surface. There are models with shapes designed to match the installation equipment, and models enabling air transport by reducing their magnetic field extension. The existence of a holder concentrates the lines of magnetic force between the magnet and holder, generating a greater holding force than the magnet alone. But since the lines of magnetic force have a small range, care is needed to prevent gaps between the magnet and held object.