Rainbow 302 Double-Layer Flip-Flop Sandals The 302 Double layer sandal by Rainbow features more cushioning and more arch support than the popular 301 single-layer. Built to last, the layers are triple glued, the straps are double stitched with bonded nylon thread, and the nylon toe piece is box-x-stitched to the straps. As this sandal breaks in, it also molds to your foot. The longer you have them, the better they feel! Leather uppers/leather footbed. Imported.