The R133 Open is a sub-miniature, single-row deep groove ball bearing specifically manufactured for environments that demand the absolute lowest possible friction torque. Built to imperial (inch) dimensions, this incredibly small bearing features a completely unshielded and unsealed design. By entirely exposing the inner raceways and rolling elements, the R133 Open eliminates the drag typically caused by protective shields. This unrestricted configuration allows for extreme free-spinning capabilities and rapid heat dissipation, making it an essential component for highly sensitive precision instruments housed in clean, debris-free environments.