The Setta are Japanese traditional sandals which have been worn from centuries in Japan. The surface is made from cotton, the same material as a traditional Japanese Furoshiki. The sole could be made out of leather, cloth, or straw.
According to the Shoninki shinobi manual, most people would advise against wearing setta sandals at night, but Natori claims that it masks the sound of one's footsteps and could be used to vary a shinobi's footsteps in the dark. This technique is called kutsukae (changing your footwear).