A stable composition for removing unwanted molecules from a surface comprises low-degree of substitution cyclodextrin derivatives. The device includes a post clamp mounted on a post installed on a roadside, a support bar radially coupled to an outer surface of the post clamp to be horizontally positioned, and a sign board coupled to one end of the support bar for exhibiting a desired road sign. By this, a frequency characteristic of a filter using an integrator as a component may be changed with an accuracy of Cf from Cf to Cf. 00 is satisfied at a predetermined zoom position except for a wide-angle end and a telephoto end where Yw30 denotes an image height that provides a relative illumination of 0.