Cardboard storage boxes with 81 slots (9×9) are perfect for storing tubes of 2ml or smaller in freezers, including hinge cap microtubes, screw cap microtubes, and cryo tubes. They come with an alphanumeric grid for easy sample identification and can endure freezing temperatures down to -90°C. Constructed from heavy-wall cardboard with a glossy finish, these boxes are sturdy and ideal for repeated refreezing cycles.The dimensions of the boxes are 134 × 134 × 50 mm, and they fit standard freezer storage racks commonly used in laboratories.