Arch support generally refers to the part of the insole of the shoe that raises right at the level of the arch to provide support to the midfoot. Arch support also refers to individual insole cups with a molded shape that fit the arch and are placed inside the shoe to help relieve foot or heel pain.
About T Strap Sandals:
T strap sandals are sandals characterized by a "T" formation by the straps on the top of the sandals. T strap sandals include a strap which crosses the top of the toes horizontally, while another strap cuts through the middle of the foot vertically.