It's not film, like photographic film - it's film, as in a type of filter paper that you put across the lens that blocks light. it comes in big sheets that you can cut down to size. There are filters with slots so that you can slide it in, or you can do what I did which is to cut it to the size of the UV filter and sandwich it between the uv and the the actual glass of the lens. (I am going to get a proper filter to hold it for future uses.)