Professional A4 Shipping Solutions – 9 x 12″ Grey Mailing Bags (Pack of 25)Upgrade your shipping game with our premium 9″ x 12″ (229mm x 305mm) Grey Mailing Bags. Specifically designed to meet Royal Mail Large Letter guidelines, these bags are the gold standard for e-commerce sellers looking to combine professional presentation with maximum postage savings.Why Choose Packaging365 Grey Mailers?Maximum Postage Savings: These bags are perfectly sized for A4 documents, t-shirts, and thin books. By keeping your profile slim, you can ship as a ‘Large Letter’ rather than a ‘Small Parcel,’ saving you pounds on every order.Professional & Opaque: Featuring a dark inner lining, these bags provide 100% opacity. Your customers won’t see what’s inside, ensuring total privacy and a professional “brand-new” look upon arrival.Ultra-Strong Protection: Manufactured from high-density, co-extruded polymer, our bags are puncture-resistant and waterproof. Whether it’s rain or rough handling, your items stay bone-dry and intact.Tamper-Proof Seal: Our “all-season” permanent self-seal adhesive strip creates a bond so strong it cannot be opened without leaving visible signs of tampering. Once it’s sealed, it stays sealed.Perfect For:Apparel: T-shirts, leggings, and baby clothes.Media: Books, magazines, and A4-sized brochures.E-Commerce: Ideal for eBay, Vinted, Depop, and Etsy sellers shipping non-fragile items.Also available in our mixed size packsTechnical Specifications:Size: 9 x 12 inches (225mm x 300mm approx)Quantity: Pack of 25Material: 100% Recyclable LDPE (60 Micron thickness)Closure: Permanent Self-Seal StripColor: Professional Opaque GreyThe Packaging365 Guarantee: Join over 5,000 UK resellers who trust us for their supplies. Order before 1 PM for same-day dispatch and take advantage of our wholesale rates—even on smaller packs!