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, and 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 damage and extend service life. Packaged in a storage box with steel balls sorted by size and stored in separate compartments for easy identification and organization. Note: Due to different production batches, the plastic box style may vary. Color: Silver. Material: Stainless steel. Dimensions: 10.01 x 3.99 x 1.30 cm. Package contents: 600 x 12 size stainless steel precision steel balls. Only the items listed are included; other products are not included. Note: Lighting reflections and display differences may cause slight variations in color between the image and the actual item. Measurement error allowance is +/- 1-3 cm.