These Letterbox Boxes measure 140mm x 90mm x 20mm and are ideal for efficiently sending your small, lightweight items — including mobile phones. Their compact size and sturdy design make them a perfect fit for securely shipping smartphones, fabric swatches, and other similar-sized items. Designed for extremely quick and easy assembly, simply secure your items inside within seconds using the two peel-and-seal strips at both ends, eliminating the need for any packing tape. These postal boxes fit inside Royal Mail’s Large Letter sizing to help minimise postage costs. Delivered flat-packed in bundles of 60 for efficient storage, these postal boxes are also 100% plastic-free, fully recyclable, and biodegradable, making them a perfect eco-friendly option.