Our Manilla Do Not Bend Envelopes are 238mm x 163mm and are designed to fit within Royal Mail’s small letter mailing criteria, perfect for sending photos, certificates, documents, CDs and other items than need to be kept flat in transit. A rigid 600gsm cardboard backing combined with a 120gsm Manilla paper printed “Please Do Not Bend” message on the front of the envelope helps ensure your items arrive safely by protecting them from bending, folding and damage in transit. Peel and seal closure and a wide flexible opening helps make our board backed envelopes fast to pack and flat packed in boxes of 125 envelopes per box helps them arrive with you in good condition and allow you to store a high volume of packing materials in minimum space.