Pendaflex Premium Reinforced Expanding Pocket with 3-1/2 inch pocket features fully lined extended gussets at the bottom and around sides. Letter size pocket with moisture-resistant coating provides protection against dampness and spills. Reinforcement at critical wear points avoids bursting and tearing. Acid free pocket containing paper made from 10% recycled fiber with at least 10% post-consumer fiber has double-thick front and manila lined back.