Our manilla board backed envelopes are 163mm x 238mm 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 1000 micron cardboard backing combined with a 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 125 unit boxes help them arrive with you in good condition and allow you to store a high volume of packing materials in minimum space. Order today and save with our accumulator saver box rates, free samples can also be ordered should you wish to try before you buy - if you need any help then please Contact Us