These sturdy and durable New Guardian board back envelopes feature heavyweight 130gsm paper and are printed with 'Please do not bend', making them ideal for mailing certificates, photos, artwork and more. Suitable for A4 documents, the C3 manilla envelopes also feature a strong Power-Tac peel and seal closure and convenient address window measuring 40 x 100mm. This pack contains 50 manilla envelopes.