Formatt Hitech 100x150mm (4"x6") Neutral Density Grad Soft Edge 0.9 (3 Stops) for 100mm Modular holder Firecrest holder Lee 100mm System Nisi 100mm system compatible with all 100mm holder systems 3 stop (0.9) Soft Edge graduated ND filter Soft edge filter has seamless transition at middle of filter and ideal for all landscape and horizon work Made in the UK in rugged and durable CR39 resin Compatible with Formatt Hitech 100mm , Firecrest 100mm, Lee 100mm and Nisi 100mm systems