Pro-Line's specially formulated polypropylene archival sheet film sleeves have a physical density that is less than other sleeving materials making it more pliable and gentle to your film. Strong and durable, Pro-Line won't become brittle or abrade film. Pro-Line sleeving is optically clear, color neutral, and has a unique anti-Newton ring surface that reduces distracting Newton rings as well as minimizing the actual surface area that is in contact with your film.