【Quality Assurance】These 3D Printer wheels are all original and high quality from 100% quality assurance. It is made of durable POM wheels, full metal 625zz bearings.【Future】Each plastic pulley wheels with the precision center spacers between the two bearings. It will protect the wheel when pressure is applied during wheel installation. It is normal for the ring to move, otherwise the bearing cannot rotate. This is not a quality issue.【Good Performance】These 3D printer wheels move smoothly, with low noise and high printing accuracy, which can improve the printing speed and printing effect very well.【Widely Application】It is applicable for the V slot profile of most DIY 3D printers, including, but not limited to Creality Ender 3 Series, CR-10 Series, Anet A8, Mega S 3D Printer.