Polaroid Graduated Gradual Neutral Density Grey ND9 (0.9) Square Filter Compatible with Polaroid & Cokin P Series Square Filter Holders Includes: Polaroid Graduated Gradual Neutral Density Grey ND9 (0.9) Square Filter for Polaroid & Cokin P Series Filter Holders Slides Easily and Smoothly in to the Filter Holder (Available Separately) Polaroid Brand. Not a Cokin Product.