RAINBOW SANDALS. SINGLE LAYER PREMIER LEATHER WITH NARROW STRAP. 301ALTSN-SRBR. SIERRA BROWN. The single layer premier leather sandal is made of top grade nubuck leather the top sole is embossed with the Rainbow logo. This model comes with a narrow strap also nubuck leather it is double stitched and the nylon toe piece is secured with a box X stitch all using bonded nylon thread.