The Impossible ND Film Pack filter was developed to allow ASA 600 Impossible Films to be used in Polaroid SX 70 cameras. Attaching this filter on top of the Impossible film cartridge will adjust PX 680 Color Shade or PX 600 Silver Shade films to approximately 100 ASA, and make them compatible with the SX 70 camera. The filters attach and detach easily from the cartridge, without requiring any camera modifications.