Quality Material: this board is quality, practical, strong, the thickness of the board is approximately 3 mm and can be applied as a barrier to guard items in transit from breaking. for Mailing or Packing: the flat corrugated cardboard is designed to add extra protection when shipping, use the sheets for extra protection against bending when putting important documents in the mail. Strong to Use: the flat corrugated cardboard is made of quality material, through strict process, to ensure safe and reliable use, not easy to break or deform, strong to serve you for long time. Wide Range of Applications: the corrugated cardboard sheet can be applied to reinforce and add support to keep items flat during the mailing process; The cardboard can also be applied to guard items from breaking due to collisions. Large quantity: package comes with 50 piece of corrugated cardboard in total, sufficient quantity to meet your various needs; Strong material can guard art prints, DIY photos, CDs, books, certificates, documents, paper, etc.