SIMAX3D【12Pcs/Pack】SIMAX3D 3D Printer POM Pulley Wheels 625zz, Plastic Linear Bearing Pulley Passive Round Wheel Roller Compatible for Creality Ender 3, CR-10, Anet A8, Anycubic Mega S 3D Printer

12pcs 625zz POM Pulley, Outer Diameter: 24mm; diameter: 5mm; Height: 10.2mm Please be aware there's a movable copper ring between bearings.

It's normal if the ring moves, otherwise bearing can't rotate.

It's not quality issue.

High pressure POM circle made with German tech, stronger than molding pulley.

Besides, every bearing is well oiled and tested during installation, work excellent in movement.