front shade 22 is secured along one transverse edge to the outer roller tube 74 by insertion of the edge into a slot or channel 85 extending longitudinally along the outer tube and secured thereon by an insert strip 86 at its opposite edge the shade is secured to the bottom rail 26 again by insertion of the bottom edge of the shade into a slot 88 in the bottom rail and held therein by an insert strip 89 fig6 appropriate decorative end covers 90 may be provided for enclosing the ends of the bottom rail in order to raise and lower the inner or rear shade 24 when the same is surrounded by the outer tube 74 the outer roller tube 74 defines a slot 92 through which the shade 24 extends to reduce friction on the rear shade the edges 94 of the slot 92 are coated with an anti friction coating 95 for receiving and nesting the bottom rail 25 of the inner shade 24 when the inner shade is wound on the inner tube 38 thereby to couple the inner and outer tubes together the outer tube defines a longitudinal channel 96 adjacent the slot 92 and shaped to receive the bottom rail 25 of the inner or rear shade with one edge surface thereof forming a continuation of the surface of the outer tube 74 as the inner tube 38 is rotated to wind the inner shade thereon the bottom rail 25 engages and nests within the outer tube channel 96 continued rotation of the inner roller assembly 34 by the pull cord 21 then rotates the outer roller assembly to wind the outer or front shade 22 on the outer roller tube 74 the outer or front.