Thank you for viewing! This is a square backpack shape-retaining frame. Designed specifically for the TSOG square backpack, The One, which I use. It can also be adapted to other square backpacks. Square backpacks are easy to use and have excellent design, but they tend to lose their shape. Why not go out with your backpack looking as good as new? It also eliminates the need for stuffing and other maintenance! This is especially recommended for those who have just bought a new square backpack, before it loses its shape. - Sales Information - Material: Stainless steel, no burrs Weight: Approximately 30g, varies slightly How to use: Instructions are included. Basically, just set the frame along the square backpack, but if you would like fixing tape, please let me know when ordering. .ˬ.)" ※ The One square backpack is 43cm tall and 17L. The product itself is flexible, so it should be adaptable to other square backpacks, but please consider this at your own risk. ~ Personal Impression ~ The more I use TSOG's The One, the more I appreciate this frame. It keeps the shape looking great, and it makes the square backpack much easier to organize and use.