Pyramid rods are the center shaft each tier spins around, and matching diameter and length correctly is the most important step before ordering a replacement. Measure your existing rod's diameter (our hubs are sized in bands from roughly 1-2.5mm up to 6mm and beyond) and its full length from base to tip, since rods vary by pyramid size and tier count. If your original rod is missing entirely, measuring the hub openings on each tier is the next-best way to determine the right diameter.