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Engineers, hobbyists, and repair technicians working with compact rotating assemblies often struggle to source the exact miniature bearing size they need without ordering in bulk. This listing offers a pack of 4 deep groove ball bearings in 20 model options — from MR52ZZ (2×5×2.5mm) to MR149ZZ (9×14×5mm) — so you can get precisely what your build requires without overstocking.
Each pack contains 4 identical deep groove ball bearings featuring a chrome steel (GCr15) raceway and double metal shields (ZZ designation). Inner diameters range from 2mm to 9mm (approx. 0.079″–0.354″), outer diameters from 5mm to 14mm (approx. 0.197″–0.551″), and widths from 2.5mm to 5mm (approx. 0.098″–0.197″). The ZZ shield keeps grease in and contaminants out without the added drag of rubber seals.
These miniature ball bearings are widely used in RC car wheel hubs and steering pivots, 3D printer extruder idlers and carriage rails, small DC motor end caps, drone arm pivots, and precision instrument spindles where low friction and compact dimensions are critical.
| Bearing Type | Deep Groove Ball Bearing |
|---|---|
| Shield Type | Double Metal Shield (ZZ) |
| Raceway Material | Chrome Steel (GCr15) |
| Inner Diameter (ID) | 2mm – 9mm (0.079″ – 0.354″) |
| Outer Diameter (OD) | 5mm – 14mm (0.197″ – 0.551″) |
| Width (Thickness) | 2.5mm – 5mm (0.098″ – 0.197″) |
| Available Models | MR52ZZ, MR62ZZ, MR63ZZ, MR72ZZ, MR74ZZ, MR83ZZ, MR84ZZ, MR85ZZ, MR93ZZ, MR95ZZ, MR104ZZ, MR105ZZ, MR106ZZ, MR115ZZ, MR117ZZ, MR126ZZ, MR128ZZ, MR137ZZ, MR148ZZ, MR149ZZ |
| Quantity per Pack | 4 pieces |
| Lubrication | Grease-packed (factory pre-lubricated) |
| Operating Temperature | See variant options |
| Dynamic Load Rating | See variant options |
| Dimensional Standard | MR-series (metric miniature) |
Match the model number to your shaft diameter (ID), housing bore (OD), and available axial space (width). For example, if your shaft is 4mm, your housing bore is 8mm, and you have 3mm of axial clearance, select MR84ZZ (4×8×3mm). Always measure your existing bearing or machined pocket before ordering.
ZZ indicates double metal shields — one stamped steel shield pressed into each side of the outer ring. The shields retain factory grease and block coarse contaminants. Unlike rubber seals (2RS), ZZ shields do not contact the inner ring, so friction and heat generation are slightly lower, making them well-suited for higher-speed, lower-load applications.
Metal-shielded (ZZ) bearings are not fully waterproof. In wet or high-humidity environments, consider applying a compatible bearing grease after installation or upgrading to rubber-sealed (2RS) variants. For occasional light moisture exposure, the factory grease provides adequate short-term protection.
Yes. MR-series miniature bearings are a standard fit in many FDM printer designs. Common applications include extruder idler arms (often MR105ZZ or MR115ZZ), belt tensioner pulleys, and Z-axis lead screw supports. Confirm the ID, OD, and width against your printer's BOM or CAD files before ordering.
Maximum permissible speed varies by model size and lubrication. Smaller-diameter bearings (e.g., MR52ZZ) typically support higher RPM than larger ones. As a conservative guideline, grease-lubricated MR-series bearings in this size range are rated for approximately 20,000–60,000 RPM depending on model. Contact us to confirm speed ratings for your specific model if your application is speed-critical.
In most cases, yes. MR-series bearings follow standardized metric miniature dimensions, so they are direct drop-in replacements for OEM bearings of the same model number. Verify the model number printed or stamped on your existing bearing before ordering to ensure an exact dimensional match.
Most hobby and light-industrial assemblies use bearings in pairs or sets of four — RC wheel hubs, dual-shaft motors, and 3D printer gantry systems are common examples. A pack of 4 covers a complete replacement set for these assemblies and provides spares for future maintenance without requiring a separate reorder.
🛒 Select your Model IDxODxThick above, then add to cart.
