10 × SMR74ZZ ABEC 9 precision stainless steel ball bearings (shielded both sides, ZZ) Product details Model: SMR74ZZ Quantity: 10 pieces Precision rating: ABEC 9 Construction: stainless steel Shielding: ZZ (metal shields on both sides) for protection against dust and debris Sizes included (inner Ø × outer Ø × width, mm): 4 × 7 × 2.5 3 × 6 × 2.5 3 × 8 × 4 4 × 9 × 4 6 × 10 × 3 9 × 17 × 5 8 × 14 × 4 Note: related SMR128 8 × 12 × 2.5 open bearings (no shields) are available in the same product family Key benefits — why you need these bearings High-speed, low-friction performance: Tight ABEC 9 tolerances deliver smooth, quiet rotation and reliable operation at elevated speeds. Corrosion-resistant durability: Stainless steel construction resists rust and extends service life in a range of environments. Reduced maintenance: ZZ metal shields keep out dirt and limit lubricant loss, reducing cleaning and re-lubrication frequency. Versatile kit: Multiple common sizes in one set let you repair or prototype across several housings and shafts without buying individual bearings. Practical performance points Smooth rotation under precision loads; suitable for small, fast-rotating components. Shields provide a balance: protection from contamination while allowing higher-speed operation compared with sealed rubber-contact types. Durable for repeated assembly/disassembly and long-term mechanical use. Typical applications — specific use scenarios RC vehicles and drones: Replace wheel hub or motor shaft bearings to restore smooth rolling and reduce vibration in model cars, trucks, and quadcopters. Desktop CNC and 3D printers: Use as idler or guide bearings for precision axis movement, improving print and cut accuracy. Robotics and instrumentation: Support small-diameter shafts in servos, gimbals, optical mounts, or other precision linkages where low friction and repeatable rotation are required. Compatibility and installation tips Verify inner diameter (bore) and outer diameter match your shaft and housing dimensions before installation. Confirm the ZZ (metal shield on both sides) suits your mounting: shields provide contamination resistance but are not fully sealed against liquids. For applications needing open bearings, the related SMR128 8 × 12 × 2.5 Open bearing is available in the same family. Press-fit or gentle heat/cold methods are recommended for tight housings; avoid impact or hammering directly on the bearing race to prevent damage. Re-lubricate as needed for heavy-load or high-temperature service; shields slow lubricant loss but do not eliminate it. What’s included Ten SMR74ZZ bearings in the sizes listed above No changes have been made to model numbers, specifications, or intended functions.