To use these sleeves, simply slide your standard-sized cards up to 63x88 mm into them. You can use them for single or double sleeving your cards. When storing, keep them in the provided sturdy cardboard box which can hold many cards. Make sure to handle the sleeves gently to avoid any damage. To maintain them, keep them in a dry and cool place. These sleeves are PVC-free and acid-free, so they're safe for long - term card storage.