Available in the United States since the early 70's, Birkenstock sandals are known for being extremely comfortable and have enjoyed a certain amount of loyalty from nurses, doctors, and others who spend a great deal of time on their feet. This comfort is derived primarily from the characteristic foot base, which is made from cork and rubber. The combination of materials conforms to the shape of the wearer's foot, giving the sandals a custom-made feel. With proper care, your Birkenstock sandals can last for years. Cork Life to maintain the life of the cork footbed is very important. Also waterproofing your leather will help to keep your birkenstocks looking new for many years to come.