10pcs 608 684ZZ 685 686 687 688 689RS 2RS Miniature Ball Bearing Shielded Skate Bear Steel Radial Deep GrooveHigh hardness and toughness: Bearing steel is a high-quality steel that is specifically designed for bearing applications. It is characterized by its high hardness and toughness, which makes it an excellent choice for applications that require high load-bearing capacity and durability. Design:This high-performance bearing features inner and outer races machined from hardened stainless steel and polished balls made of premium chrome steel for incredibly smooth, reliable operation even under extreme loads.Versatility: These bearings are widely used in a variety of small machinery applications, including skateboard wheels, inline skates, and electric motors.Easy Installation : The compact integrated corrosion resistant stainless steel construction allows for quick press fit installation into tight spaces without the need for fastening hardware or bonding agents.Superb Performance : The meticulous hand-finishing and quality craftsmanship provide virtually frictionless, vibration-free and whisper-quiet spinning, making this bearing the smart choice for the most critical industrial equipment where failure is never an acceptable option.