Our Smart Cover II Rigid Paperback Bk Covers allow you to turn a paperback into a hardcover bk in seconds, plus save time and your bk budget. They take less than 30 seconds to apply. The acid-fee, delayed-action, repositionable adhesive allows ample time to reposition the cover. Both the cover and adhesive are crystal clear and non-yellowing. The extra-thick, 2-piece, 15-mil polyester covers have a flexible, 2-mil spine strip which protects without extra weight; bks will not fan open. The covers are fully adjustable and will fit thin or thick paperbacks. The product is also environmentally-friendly with recyclable release liners.