Abstract: Several keys (A) are spaced along the profile (C), having opposite flanges, which are connected to the profiles by rotation. There is a key-shaped flange on one side (1) and a disc-shaped flange on the other (4), connected by a neck (3) with an intermediate rotation key (2). Said disc-shaped flange (4), has a modified disc-shaped form with elastic interference protrusions (42) on two orthogonal axes (X/Y) respectively coinciding one or the other (X--X) with the plane passing on the longitudinal axis of said key-shaped flange (1). After having inserted the disc-shaped flange of the key (4) inside the same first profile (C) and having rotated it 45 degrees in respect to the interference axis in the first profile (Z1/Z2), said keys can scroll freely (A) inside the respective groove of the first profile (C).