Abstract: A double-layer roller blind includes a first roller and a second roller horizontally arranged in parallel at the top side of a window, a first shade fastened with a top edge thereof to the first roller, a first bottom bar fastened to a bottom edge of the first shade, a second shade fastened with a top edge thereof to the second roller, and a second bottom bar fastened to a bottom edge of the second shade and suspended below the first bottom bar. The first bottom bar is provided with an insertion space through which the second shade is inserted such that the second shade is kept close to the first shade.

Abstract: A slat set for a window blind includes a plurality of serially alternatively arranged odd-numbered slats and even-numbered slats. The odd-numbered slats each have a cross section having a midpoint, a recessed portion at a left side of the midpoint, and a raised portion at a right side of the midpoint. The even-numbered slats each have a cross section having a midpoint, a raised portion at a left side of the midpoint, and a recessed portion at a right side of the mid point.