Magnetic resistance models control resistance by means of permanent magnets or electromagnets. These magnets can be permanent magnets or electromagnets. The force is particularly sensitive to rotations of the magnets due to magnetic torque. Magnetic separation follows, with a series of magnets of increasing strength. The poles are supplied by direct current or magnetized by permanent magnets. They require large magnets and coils to increase force. The rotor however has no magnets or coils attached. The system is also lighter because the use of high grade neodymium magnets. It has a higher saturation magnetization than the ferrite magnets. Strontium carbonate is used in the manufacturing of hard ferrite magnets. Rotten had a store that carried t-shirts, mousemats, stickers, magnets, and bizarre DVDs. Both types have a central rotor containing permanent magnets. A second arrangement has the rotor winding basket surrounding the stator magnets. The simplest example of this is the attraction of opposite poles of two magnets. It consists of a periodic structure of dipole magnets.