Quality Park Jumbo Envelopes – Catalog – 14″ X 18″ – 28 Lb – Kraft – 75/Box Extra large envelope is ideal for storing a wide variety of materials. Ungummed flap makes it ideal for interoffice use. Heavyweight paper stock. Envelope Size: 14 x 18 Envelope/Mailer Type: Catalog/Clasp; Closure: Ungummed Flap.