These Letterbox Boxes measure 305mm x 220mm x 20mm and are perfect for efficiently shipping your small, lightweight items — particularly A4-sized products such as documents, brochures, books, and prints. Their generous dimensions provide a snug and protective fit for flat A4 items, making them ideal for businesses sending paperwork, marketing materials, or slim merchandise. They’re also an excellent choice for sending fabric swatches, especially larger samples that need to remain flat and presentable during transit. Engineered for fast and simple assembly, you can secure your items in seconds with the two peel-and-seal strips at both ends, eliminating the need for packing tape. Designed to fit within Royal Mail’s Large Letter size, these boxes help reduce postage costs. They are delivered flat-packed in bundles of 40 for convenient storage and are 100% plastic-free, fully recyclable, and biodegradable, making them an excellent eco-friendly choice.