Medical devices are classified into Class I, II, and III. Regulatory control increases from Class I to Class III. The device classification regulation defines the regulatory requirements for a general device type. Most Class I devices are exempt from Premarket Notification 510(k); most Class II devices require Premarket Notification 510(k); and most Class III devices require Premarket Approval. A description of device classification is available at "Classification of Medical Devices."
Class I devices present a low risk of harm to the user and are subject to general controls that are sufficient to protect the user. Most are typically exempt from submitting a 510(k), but still need to comply with other regulations, such as QSR, Registration and Listing (R&L), etc.
Class II devices are those for which general controls alone are not sufficient to assure safety and effectiveness, and existing methods are available to provide such assurance. (Predicate devices). They are also subject to special controls.
Class III devices present a high risk of harm to the user and are usually used to sustain or support life, are implanted, or present potential unreasonable risk of illness or injury. Most of these devices require PMA (Pre-market Approval - see Step 3) because general and special controls alone cannot reasonably assure their safety and effectiveness.