The refill pages is a protective jacket, cardboard inside the main problem is the high humidity will variant, PVC is not affected by water, than paper thin many, so popular with many people, for the carrier don't pursuit of material, as long as durable, light and not variant can be PVC mainly has two kinds of black and white, can see from the cut surface of the album, also can do plane hot stamping, spray can also do all sorts of color of the retailer