Engineered for highly restricted spatial requirements, the R156-ZZ is an ultra-compact imperial ball bearing that delivers flawless rotational accuracy in a miniature footprint. By incorporating two non-contact steel shields ("ZZ"), this bearing effectively safeguards its internal raceways from dust and external particulates while permanently retaining its factory lubrication. With its exact 3/16-inch bore and exceptionally slim 5/16-inch outer diameter, the R156-ZZ is the definitive solution for engineers seeking to minimize weight and save critical space in micro-mechanical assemblies without sacrificing durability.