Formatt Hitech Limited HT100NDMKit Neutral Density Master Kit 4 Soft Edge Master Kit (6 Filter Combined Neutral Density Standard and Graduated) Neutral density filters produce a grey neutral tone and are used in photography to reduce light This 100mm filter kit is usable with Hitech 100mm holder systems or any 100mm holder The kit is also available in 85mm, 150mm and 165mm sizes