This is an ammunition box for 223 / 556 caliber. The cartridges snap into place nicely and hold securely without rattling during transport. The boxes are stackable and provide optimal protection for the cartridges. The labeling can be customized in the slicer. I recommend PETG as a material. I glued in magnets (3mm in diameter) to make them stackable. If you want I can draw connectors for plugging in the holes. With glued-in magnets they even stick to metal walls.