Birkenstock Original Comfort Footbed Insoles - Regular Width, Black, Size 47 (US Men's 13) - Arch Support for All-Day Comfort - Perfect for Work, Walking & Standing Long Hours

The blue insole uses the same principle as walking barefoot and was designed on the basis of the footprint left by a healthy foot on the sand. In this way the natural condition of foot support is recreated. The heel area is adequately cushioned and stabilized