This is the rising star of the magnet world allowing having a much greater ratio of power to weight. Smaller motors and other assemblies can therefore be designed. NdFeB (Neodymium) magnets are fragile, susceptible to corrosion (normally supplied coated) and have working temperatures from 80-200 degrees Celsius. For higher working temperatures the more expensive Samarium Cobalt (SmCo) is used. Both NdFeB and SmCo are available in sintered as well as bonded forms. The bonded form of the material can be produced with close tolerances requiring little or no finishing. The sintered form usually requires some finishing operations in order to adhere to close mechanical tolerances.