





📬 Elevate your mail game — protect, seal, and impress every time!
Blake Purely Packaging C3 Board Back Peel & Seal Envelopes (Pack of 50) offer robust protection for flat mail items with their heavy-duty board backing and secure peel & seal closure. Sized at 450 x 324 mm, these manilla envelopes feature a clear 'Please do not bend' print to ensure careful handling. Made from 100% recycled materials, they combine durability, eco-friendliness, and professional presentation, making them a top choice for safeguarding certificates, photographs, and important documents.





| ASIN | B00O4X7W00 |
| Best Sellers Rank | 5,706 in Stationery & Office Supplies ( See Top 100 in Stationery & Office Supplies ) 93 in Envelopes |
| Brand | Blake |
| Closure | Self-Seal |
| Colour | Manilla |
| Customer Reviews | 4.6 4.6 out of 5 stars (2,279) |
| Date First Available | 23 Sept. 2014 |
| Item Weight | 2.49 kg |
| Manufacturer | Blake Envelopes |
| Manufacturer Part Number | 4200/50 |
| Material Type | Cardboard, Cardstock, Paper |
| Model Number | 4200/50 |
| Number of Items | 50 |
| Paper Finish | Uncoated |
| Product Dimensions | 46 x 33.5 x 10.5 cm; 2.49 kg |
| Shape | Rectangular |
| Sheet Size | C3 |
| Size | C3 450 x 324 mm |
| Total Recycled Content | 100 |
T**R
The only brand of board backed envelopes I will buy
Excellent board backed envelopes, with 'please do not bend' printed clearly on them. I made the mistake recently of buying a cheaper alternative and definitely regret it. (For the saving of several pounds, I am now stuck with more than 100 flimsy, bendable envelopes with an unpleasant font on the front!) Both the grey board and the brown kraft paper used are of decent thickness to protect most flat items. They are also durable and reliable. Would definitely recommend. Although, for e.g. single prints, they might still need cardboard stiffeners so bear this in mind.
V**.
Great product
Very durable, functions well. Seals very well. Postage is protected. Great value for money. Brought many times. Light brown colour. Can be used for cards and large letter. Lightweight
P**Y
Quick delivery
Quick delivery at a good price
A**R
Good quality envelopes
Nice product perfect for my needs
D**R
Thinner than ideal but OK
Card is not the heaviest duty, advise an additional stiffener if it's important using Royal Mail, which of course is a chore. However, by comparison to Rymans who I used to use, they are not bad value and I bought some card stiffener to insert as needed. Extra cost yes, but overall it works OK for my business.
A**L
Arrived quickly.
I bought the envelopes to post knitting patterns. They could of been a tiny bit stronger But with what I paid for them I am happy.
B**S
Good envelopes
They are envelopes for A4 paper good adhesion and fit within the large letter category the cardboard back provides durability and protection so are quite useable for things you wish to protect in postage whilst not adding much to the overall weight of the letter therefore minimising postal costs
C**R
Excellent quality!
I use board back envelopes regularly and have tried a few suppliers for these. Oftentimes, the board quality can be too thin and cheap, which isn't ideal for something you need to protect during transit through the postal system. However, I'm pleased to say that the quality of this pack is absolutely spot on. Decent gsm Kraft paper and grey board means I have confidence using these and would be happy to recommend them. I'll order again when my current box runs out and hopefully they'll have kept up the same great quality.
P**A
Ordered them in The Netherlands in October 2022, for my small art prints business. The the carton part is a liiitle bit thiner than the previos envelopes I ordered (the same brand), which I like even more. It IS thick enouph and does not bend under its own weight. Will definitely order again :)
D**O
Estupendo para enviar billetes o pequeños documentos que no quieres que se doblen. No me gusta las letras impresas abajo: "Please do not bend"( por favor no doblar) Me hubiera gustado que fuera en Castellano o que no pusiera nada.No me di cuenta de esto cuando los compré. Aparte de eso , son unos sobres mágnificos y muy baratos.
E**I
Wie erwartet
L**Z
Decent chipboard thickness. I use them to ship out stickers. Keep in mind that it doesn’t extend all the way, the dimensions of the chipboard area is probably around 4”x6”
A**E
This item was arrived exactly it was described. It will definitely serve the purpose and I am satisfied with the purchase.
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