PU69310-4 3X10X4 PU Polyurethane Wheel U Groove Pulley Rubber Coated Bearing 693zz. Rubber Coating Protection: Provides sealing, wear resistance, noise reduction, and corrosion prevention. Weather Resistance: Strong resistance to ozone and atmospheric aging for outdoor use. Low Noise Performance: Ensures stable operation with reduced friction and noise. Multiple Inner Diameters: Available in 5mm, 6mm, 8mm, and 10mm sizes upon request. ISO Certified Quality: Manufactured with ISO certification for reliable performance. OEM and ODM Services: Customization services available for specific requirements. Diverse Material Options: Includes polyurethane, silicone rubber, and polyacetal (POM).