HIGH QUALITY: Made of high quality bearing steel, durable with the resistance of wear and collision. FEATURE: It is characterized by small frictional resistance and high rotational speed and can be used on mechanical parts that are subjected to radial loads or axial loads, such as machine tool, electronic equipment, ect. GOOD DESIGN: Exquisite design, two sides metal sealed ball bearing, with good dustproof effect. Built-in precise micro bearing provides smooth running and long service life. GOOD DESIGN: Exquisite design, two sides metal sealed ball bearing, with good dustproof effect. Built-in precise micro bearing provides smooth running and long service life. SATISFACTION GUARANTEE: We care for every customers feeling.If this product does not meet or exceed your expectations,please send it back for a 100% refund no questions asked. SMR103CB 3*10*4mm SMR115CB 5*11*4mm