Our Matted Photo Sleeves are made from bioriented polypropylene (BOPP) material which means that it is as clear as glass and will not ripple, dimple, or pucker over time as some polypropylene materials will. Our polypropylene has passed the Photo Activity Test (P.A.T.) which certifies that it is safe for long-term storage. All sleeves come with a resealable flap. The reseal tape is on the body of the sleeve.