The feminine Granada characterized with its two perforated adjustable straps is sometimes referred to as the "butterfly" style. The slight dip in the arch strap gives room for a higher instep.
Oiled leather can be recognized by its untreated surface. Birkenstock purposely does not treat surface grains and other characteristic features. Birkenstock uses sturdy leather with a thickness of 2.8 to 3.2 millimeters as upper material.