Miniature Bearings, Ultra Thin: The inner diameter is larger than normal radial ball bearings.The most multi-directional deep ball bearing in the bearingsDeep groove ball bearings have a deep arc groove on both inner and outer wheels and are suitable for high-speed rotations. Inner diameter: 0.2 inches (5 mm). Outer diameter: 0.3 inches (8 mm). Thickness: 0.1 inches (2.5 mm). Weight: 0.2 oz (5 g). Material (body): Made of stainless steel, which is abrasion resistant and resistant to collision.Built-in precision micro bearings for high stability and long lifeHigh Quality: It has excellent high temperature resistance up to 244°F (120°C).Standard size used in machine tools, electronics, pump industries, airships, decelerators, plastic machinery, motors, textile machinerySet Contents: 10 pieces.