ISF FSN and CSN SQ 67mm square filter in case for Pro4 and Cokin A series holders. Pair of Neutral filters. The FSN offers a Gentle full frame softening effect and the CSN has gentle foreground softening. They're ideal for professional quality portrait and wedding photography. Place the filter close to the lens as possible for best effect. Use on lenses between 35 and 70mm on 35mm format and full frame digital, or 60 and 100mm on medium format. Using an aperture between f/2.8 and f/5.6
marks around edges where they've been inserted in filter holder, no affect on photos.