12 size precision steel balls assortment kit contains: 90 pcs 1mm, 80 pcs 2mm, 80 pcs 2.5mm, 50 pcs 3mm, 50 pcs 3.5mm, 50 pcs 4mm, 50 pcs 4.5mm, 50 pcs 5mm, 30 pcs 5.5mm, 30 pcs 6mm, 20 pcs 7mm, 20 pcs 8mm. Made of 304 stainless steel. Uniform size, high wear resistance, high precision, smooth surface, no burr, excellent appearance. Widely used in auto parts, motorcycles, bicycles bearings, casters, drawer slides, etc. Can also be used as mixing balls for stirring paint, nail polish, and similar applications. Surface coated with a small amount of grease to reduce friction during bearing rotation and to prevent corrosion and rust. Helps reduce machine wear and extend service life. Supplied in a storage box with compartments for organized, size-sorted storage. Easy to identify and access. Color: Silver. Material: Stainless steel. Dimensions: 10.01 x 3.99 x 1.30 cm. Package includes: 600 pcs stainless steel precision balls in 12 sizes. Box only contains the steel balls; other items not included. Note: Lighting and display differences may cause slight color variations between the image and the actual item. Measurement tolerance: +/- 1-3 cm.