The new Impossible ND Film Pack filter was developed to use 600 ASA Impossible Film in Polaroid SX 70 cameras. Inserting this filter on top of the Impossible film cartridge will adjust all PX 600 and PX 680 films to approximately 100 ASA and make them compatible with your SX 70 camera. It will also work with the new PX 70 film, as an alternative to the adjustment of the lighten/ darken wheel. This filter is easy to attach, detach and use and does not require any changes to the camera itself.