MATERIAL: 12x9x4 box is made of recyclable corrugated cardboard, which is lightweight but sturdy, ensure your stuff safety. DIMENSION: The shipping boxes set includes 20 packs of the cardboard box. The outer size of this mailer box is 12” x 9” x 4”(L x W x H), the inner size is 11.6" x 8.9" x 3.8". Suitable for packing or mailing those small and lightweight items. Assembles in seconds without tape, glue, or staples. USAGE: It is perfect for mailing or shipping small soaps, toys, biscuits, or other small items. You can arrange these boxes as you like. APPEARANCE: The edges are neat, smooth and no burrs, the product looks very beautiful as a whole.