Clear 'n' Easy Book Covers come in individual sheets or on rolls. Made from 1.5 mil archival polyester. Polyester material will not yellow or become brittle over time, even in direct sunlight.Both the individual sheets and the rolls have a pre-folded 1-1/2" flap on one long edge. Simply insert book jacket under the pre-folded edge and fold other long edge over book jacket cover. Covers come with an optional use adhesive tab to keep the cover in place.