Our new F-Flute mailing boxes are 30% stronger and weigh 30% less, potentially lowering your shipping costs. These sturdy boxes are tight-wrapped with our 100% recycled PaperKraft™ 100 paper. Our 3 stock gummed flap mailers don’t require any additonal tape to seal the box. Just moisten the 4 flaps and completely seal the box. Perfect for Registered mail packages.