The Lee Filters 24 x 21" 1/2 Shanklin Frost Diffusion Filter Sheet offers a range of solutions for softening and spreading a light beam, thus reducing the contrast ration between highlight areas. The Lee Filters 24 x 21" 1/2 Shanklin Frost Diffusion Filter Sheet is a part of a range that includes polyester diffusion filters, frosts, flexi-frosts, perforated diffusion, grid clothes, and spun materials, which are all offered in different densities for a wide range of lighting effects.