Check the definition of medical devices. Medical devices refer to instruments, equipment, appliances, in-vitro diagnostic reagents and calibrations, materials and other similar or related items directly or indirectly used in human body, including required computer software. Their utility is mainly obtained by physical means, not by pharmacology, immunology, metabolism and other means, or although they participate in these ways, they only play an auxiliary role. Note that various options are split according to this definition, and pay attention to this propositional method.