The R166-ZZ is a highly versatile inch-series miniature ball bearing designed for environments where both reliable rotation and protection from airborne debris are critical. By utilizing a double-shielded ("ZZ") configuration, this bearing effectively locks in factory-applied grease while blocking dust, dirt, and fine particulate matter from entering the raceways. With its standard 3/16-inch bore, the R166-ZZ is an essential, maintenance-free component for compact electric motors, hobbyist models, and precision commercial equipment requiring sustained, smooth performance without regular relubrication.