Among professional photographers seeking to preserve their work, Clearfile archival quality storage and presentation sheets are extremely reliable and cost-effective. Clear File uses a specially formulated polyethylene and polypropylene so that their products provide maximum long term protection for delicate photographic emulsions. Clear File's museum quality, archival pages are acid free (pH Neutral) and contain none of the platicizers, catalysts or solvents that can potentially harm prints and transparencies. Fits most standard 8.5 x 11 3-ring binders and albums Sturdy 4 mil polypropylene Made in USA