From Birkenstock, the Men's Blue Footbed Insoles feature: New Blue Footbed Insole features 4 layers of comfort and support The top layer is microfiber for climate and moisture control  The ¾ length cork layer is anatomically shaped core stabilizer that ensure optimal pressure distribution The woven jute layer supports the core stabilizing function The last layer features shock absorbing PU which reduces the pressure points and promotes natural foot motion Imported.