Filter Holders for reflector size 19.7x8.3 in/50x21 cm Kaiser Filter Holders Guiding rails for slide-in filters: Diffusion Screens (205583) and (205593) and Polarizers (205594).Compatible with reflector size 19.7x8.3 in/50x21 cm: Lighting Units (205556, 205557, 205558, 205588, 205867, 205868). 2 pairs.