The PMOA for a combination device determines the lead agency center .The component that contributes the most to the combination device’s intended therapeutic effects determines lead agency center. If PMOA is unclear ,a request for RFD can be filled.This will help to established lead center of combination device.After receiving RFD ,FDA will assign device to agency center that regulates other similar product,if no similar product exists,FDA will assign to agency center with most expertise to evaluate safety and effectiveness of combination device.