S684ZZ stainless steel ball bearings in a 4x9x4 mm size, packed as 10 pieces, with ABEC7 precision and 440C stainless steel construction. These bearings feature ZZ shields on both sides to help keep contaminants out while preserving lubrication, supporting reliable and smooth operation in compact assemblies. Key benefits precision for smooth, lowfriction movement in tight spaces thanks to ABEC7 tolerances. Corrosion resistant 440C stainless steel for durability in moistureprone or demanding environments. Shielded on both sides (ZZ) to reduce contamination risk and simplify maintenance. Durable stainless steel construction designed for repeated cycles and longer service life in hobby and smallscale applications. Convenient 10piece pack for multispot installations or spare parts. Key attributes Size: 4 x 9 x 4 mm (inner diameter 4 mm, outer diameter 9 mm, width 4 mm) Bearing type: Ball bearing with shields ZZ on both sides Material: 440C stainless steel ABEC rating: ABEC7 Model references: S684Z, S684 Z, ZZ Package quantity: 10 pieces What's included 10 bearings per pack, ready for use in compatible assemblies Applications and use cases Miniature robotics and hobby projects that require compact, precise bearings in gearboxes or rotating joints 3D printer components such as idler wheels, bearing housings, or moving parts where space is limited and reliability matters RC models, drones, or small machinery where durable, lowfriction bearings are needed in tight spaces Installation and compatibility notes Suitable for standard 4x9x4 mm bearing replacements in compatible housings and shafts For performance, apply appropriate lubrication according to the specific application and operating conditions, and follow general maintenance practices to extend bearing life These S684ZZ bearings offer a reliable combination of compact size, corrosionresistant stainless steel, shielded protection, and precision tolerance, making them suitable for a wide range of small, demanding applications while maintaining clear alignment with the original model and features.