Self-seal mailers have peel-off adhesive strip. No tape or stiffeners needed.First class presentation guaranteed.Postage savings due to light weight.Will not bend or crush.Convenient pull-tab tear strip. DIMENSIONS:Dimensions do not include flap.4 is the industry standard # for that size mailer.Usable: 12 1/4 x 14 3/4″Based on contents no more than 1/4″ thick.THICKNESS:.028″ MATERIAL:Clay coated newsback Semi-gloss coating RECYCLING:Recycled Content: 100%Post-consumer: Minimum 35%