Neewer FL-20 Neutral Density Filter Sheet Set (15.7 x 19.7") ND3: 1-Stop, Filter Factor 0.3, ND6: 2-Stop, Filter Factor 0.6, ND9: 3-Stop, Filter Factor 0.9, Easily Cut 15.7 x 19.7" Polyester Film LIGHT MODIFIERS-Color Correction Filters & Gels