R188KK U-Groove Miniature Ball Bearing High-Speed Centering Bearing | 1/4" x 1/2" x 3/16" (6.35x12.7x4.762 mm)

The R188KK is a highly specialized miniature deep groove ball bearing distinguished by its unique U-groove (concave) outer profile. Primarily engineered for high-performance yo-yos, fidget spinners, and precision micro-mechanics, this inch-sized component guarantees optimal string centering and prolonged spin durations. Boasting standard dimensions of a 6.35mm bore (1/4"), 12.7mm outer diameter (1/2"), and 4.762mm width (3/16"), it provides ultra-smooth, low-drag rotation. Designed to sustain intense speeds, the R188KK serves as an essential upgrade for unresponsive yoyo play and demanding compact mechanical setups requiring a dependable bearing solution.

Engineered to bridge the gap between compact dimensions and substantial load capacities, the R14-ZZ is a highly versatile inch-series deep groove ball bearing. Featuring twin pressed-steel shields (ZZ), this model efficiently deflects dirt and metallic debris while keeping the internal factory lubricant securely in place. Because these metal shields operate without making physical contact with the inner ring, the R14-ZZ minimizes mechanical drag and startup resistance, making it an optimal 7/8-inch bore solution for electric motors, gearboxes, and high-speed automated machinery.

Manufactured specifically for mechanical environments prone to heavy dust, moisture, and particle contamination, the R14-2RS is a premium inch-system deep groove ball bearing. Unlike metal-shielded variants, this model is equipped with dual synthetic rubber contact seals (2RS). The sealing lip makes direct contact with the bearing's inner ring, creating an impenetrable barrier against harsh external elements while permanently locking in the specialized factory grease. This makes the R14-2RS the ultimate choice for standard 7/8-inch shaft assemblies in food processing lines, liquid pumping systems, and heavy outdoor equipment where contamination control is critical.

Engineered to deliver exceptional radial support and smooth rotational efficiency in fractional-inch machinery, the R4A-ZZ is a premium single-row deep groove ball bearing. Outfitted with dual pressed-steel shields (ZZ), this bearing effectively blocks external debris while safely retaining its factory-engineered lubricant. Because these metal shields operate without direct contact against the inner ring, the R4A-ZZ minimizes mechanical drag and starting torque, making it a standout selection for 1/4-inch shaft applications including precision gearboxes, optical instruments, and medical apparatus.

Engineered for fractional-inch applications requiring exceptional durability and environmental defense, the R4A-2RS is a high-quality, single-row deep groove ball bearing. Outfitted with heavy-duty double rubber contact seals (2RS), it provides superior protection against the ingress of dust, dirt, and moisture while securely locking in the factory-applied lubricant. Because the rubber seals maintain direct contact with the inner ring, this bearing offers maximum contamination resistance, making it the ideal solution for 1/4-inch bore mechanisms operating in demanding or exposed environments, such as electric motors, power tools, and automated manufacturing equipment.

Built for high-precision operations in compact fractional-inch assemblies, the R3A-ZZ stands out as a top-tier double-shielded deep groove ball bearing. Equipped with twin metallic shields (ZZ), it forms a highly effective barrier against airborne dust and contaminants while securing the factory-applied lubricant inside. Because these metal shields are engineered to hover just above the inner ring without physical contact, the R3A-ZZ ensures minimal rotational drag and virtually zero start-up friction. This makes it a critical component for 3/16-inch bore applications like aerospace avionics, delicate medical instruments, and miniature gearboxes.

Designed for confined mechanical spaces demanding exact shaft positioning, the FR168-ZZ is a high-grade miniature deep groove ball bearing equipped with a specialized flanged outer ring. Featuring twin non-contact metal shields (ZZ), this component provides outstanding protection against environmental contaminants while securely retaining its premium factory grease. Because these steel shields do not rub against the inner race, the FR168-ZZ guarantees ultra-low starting torque and frictionless, high-velocity rotation. This makes it an indispensable asset for 1/4-inch shaft applications where space is at a premium, including advanced RC models, medical handpieces, and intricate robotic assemblies.

Built for environments that demand robust load-carrying capacity and superior contamination defense, the R20-2RS is a premium inch-series deep groove ball bearing. Equipped with dual rubber contact seals (2RS), this bearing is engineered to lock in factory grease while completely blocking out moisture, dust, and abrasive particles. Because these synthetic seals make physical contact with the inner ring, the R20-2RS provides exceptional reliability in challenging conditions, making it the go-to solution for 1.25-inch bore equipment like heavy-duty pumps, industrial blowers, agricultural machinery, and conveyor systems.