The Polaroid back is one of the greatest time and money saving devices available. The Polaroid Film Pack Holder is indispensable for checking exposure, composition and lighting (especially fill flash). It is an invaluable tool for instant proofing of images for art directors and clients. Fully meter coupled with Pro AE Prism Finder. An absolute must in elaborate settings where the shoot cannot be duplicated. Compatible the the 645AF and 645AFD models only.