For your creativity: reduction of the apertures by 2 (ND4) 3 (ND9) or 4 (ND16). | Practical set of 3: consists of three extra thin filters with ND4 (0.6) ND8 (0.9) and ND16 (1.2). | Matched design: rounded corners for a perfect fit, thickness of 0.1 mm. | Universal fit: suitable for Irix lenses or other lenses with 30 x 30 mm gelatin filter insert. | Box contents: gelatin filter set for Irix lenses with 30 x 30 mm filter insert.