warm 100g insulation

The stretchy shaft is as soft as the light velour lining and the Antistress insole

Two adjustable straps with metal pin buckles

an extra layer of latex foam

Shopping for someone else but not sure what to give them

BIRKENSTOCK BLUE FOOTBED INSOLE MEDIUM Size:40 warm 100g insulationProduct Details: The Blue Footbed utilizes the principle of walking barefoot. It is based on the impression left by a healthy foot in sand, creating a natural environment for your feet. The heel area is cushioned and stabilized thanks to the raised design. This also supports the natural arch of the foot. The Blue Footbed is therefore ideal for anyone who would like to enjoy the unique comfort of BIRKENSTOCK in enclosed shoes made by other brands too.