Our Kpop postcards sleeves are made of polypropylene material, which is thick, durable, and transparent. The clear design of the sleeves allows you to see the front and back of the cards, but most importantly they are PVC Free and Acid Free. They are designed to protect your postcards from scratches, dust, and other damage, while also allowing you to display them. The sleeves are 100 microns thick, which provides excellent protection for your cards. They are perfect for collectors, fans, and anyone who wants to keep their photocards safe and organized.