BIRKENSTOCK. 1001173. FOOTBED SPORT. BLUE. The Blue Footbed utilizes the principle of barefoot walking. It is based on the cast of a healthy foot in the sand creating a natural environment for your feet. The heel area is cushioned and stabilized thanks to the raised design. It also supports the natural arch of the foot. This makes the Blue Footbed ideal for anyone who would also like to enjoy the unique comfort of BIRKENSTOCK in enclosed shoes made by other brands.