Product Function: These bearing balls are installed between the inner ring and the outer ring to reduce friction when the bearing rotates. Will reduce damage to the machine and extend the service life. High quality: It is made of high quality 304 stainless steel, high precision machine, corrosion resistant, high hardness, smooth and burr-free. Easy to carry: 12 sizes to meet your different needs, the product has the characteristics of small size, convenient to carry and store when going out to work, easy to use and good performance. Wide application: Widely used in motorcycles, bicycles, casters, home furniture, door locks, drawer slides and many other applications. Warm note: These small size balls are made of solid steel, please keep them away from children under 5 years old to avoid choking. Package includes: 2mm 80pcs + 2.5mm 80pcs + 3mm 50pcs + 3.5 mm 50pcs + 4mm 50pcs + 4.5mm 50pcs + 5mm 50pcs + 6mm 30pcs + 7mm 20pcs + 8mm 20pcs + 9mm 15pcs + 10mm 15pcs.