Medical devices are classified by regulatory bodies like the FDA based on risk levels and the controls necessary to ensure safety and effectiveness. Class 2 devices represent medium-risk products—such as powered wheelchairs, infusion pumps, and certain diagnostic equipment—that require special controls, performance standards, and premarket notification clearances. Class 3 devices represent high-risk products that sustain or support human life, are implanted, or present potential unreasonable risk of illness or injury—such as pacemakers, heart valves, and advanced spinal fusion hardware—requiring rigorous premarket approval clinical trials.