Manufactured in the UK, Blue Label Window Envelopes are a stationery essential, ideal for small business, home of office use. These white envelopes are made from 80gsm paper and are printed blue opaque to ensure contents remain confidential. Complete with an address window and handy, time-saving self-seal closure.. DL size - for A4 paper folded into thirds. White 80gsm paper. Blue opaque to maintain confidentiality. Pocket style envelope. Self-seal closure. Manufactured in the UK. Pack of 500