HARD MATERIAL - Our corrugated shipping boxes are made of premium corrugated cardboard which is hard, well made and of high quality, sturdy enough to protect the contents. Corrugated is flexible and impact resistant, providing good cushioning for your transported items. EASY TO ASSEMBLE - The foldable design made these corrugated cardboard boxes really easy to put together without using adhesive tape or staples. The neat slots allow them to close precisely, and not easily fall apart. When you are not using them, they can also be easily unfolded without taking up space. ABOUT SIZE - 50 pack brown mailing boxes in total. They have external dimensions of 15 x 10 x 6 cm, internal dimensions of 13.5 x 9.5 x 5.5 cm and a thickness of 1.7 mm. They have a distinction between positive and negative sides, with the front side being smooth and the reverse side being corrugated. MEETING DIFFERENT NEEDS - Our corrugated cardboard mailing boxes are perfect for shipping as small parcel boxes, shipping smaller items to customers or posting fragile items. The blank brown surface supports sticking labels or markers, or you can DIY them to make your own gift boxes. HAPPY BUYING - We strive to provide better after-sales service and offer a 30-day money-back guarantee. If you have any questions or dissatisfaction with the small mailer boxes, please feel free to contact us to let us know. Our customer service will get back to you ASAP within 24 hours.