Description
394 × 318 mm (≈ 15.5″ × 12.5″) Board Backed Envelopes — Bulk Rigid Mailers
For non-standard yet highly functional mailings, our 394 × 318 mm board backed envelopes deliver extra-sized protection without resorting to bulky boxes. These hard backed envelopes use 950 µm board and 115 gsm paper to ensure they stand up to the rigours of the postal system. This listing is for bulk quantities, ideal for businesses, art sellers, print houses, galleries, and any high-volume sender who needs generous format mail protection.
Features & Construction
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Size: 394 mm × 318 mm internal (approx 15.5″ × 12.5″) — large enough to carry many non-standard or oversize flat items. Defenda Packaging
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Build & materials: 950 µm rigid board core and 115 gsm paper shell give these mailers serious stiffness and protective strength. Defenda Packaging
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“Please Do Not Bend” print: Each envelope is boldly printed in red on the front to reduce mishandling. Defenda Packaging
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Envelope weight: Approx. 99.5 g per empty unit Defenda Packaging+1
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Bulk packaging: Available in tiered packs (50, 100, 250, 500, 1,000) to fit small and large mail runs. Defenda Packaging
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Peel & seal closure: Easy, fast sealing for efficient packing workflow. Defenda Packaging
Suitable Contents & Use Cases
This size hits a sweet spot for sending larger flat items, especially when A3 / C3 is overkill or when you need a more custom size. Items well suited for the 394 × 318 mm board backed envelope include:
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Oversized prints or photographs that exceed standard A3 margins
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Artwork and illustrations on medium or heavy stock
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Portfolios, presentation boards, proof sheets
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Certificates or diplomas on thick stock
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Maps, layouts, sample boards
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Multiple A4 or A5 sheets stacked or packed flat
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Marketing materials or catalogs that are larger than standard sizes
The rigid board core ensures these items arrive flattened and intact — free from bending, creasing, or edge damage.
Why Bulk Orders Are Smart
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Lower per-unit cost — buying in volume reduces your average price per envelope
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Reliable supply — ensures you’re always stocked for large mail campaigns
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Consistent quality — every envelope you use meets the same engineering standards
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Operational efficiency — faster packing, storage, and dispatch when handling many units
Key Benefits & Selling Points
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Maximum flat protection — rigid board backing withstands postal handling stresses
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Professional delivery — recipients see crisp, flat items, reinforcing your brand’s care
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Generous capacity — can accommodate items larger than typical formats without over-sizing
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Bulk orientation — tailored for high usage or recurring mailouts
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Postal clarity — “Please Do Not Bend” print helps reduce mishandling
