6308NR Nachi Bearing, Made in Japan, with a Snap Ring, the 6308NR inner diameter is 40mm, the 6308NR outer diameter is 90mm, 6308NR width is 23mm.
Deep Groove ball bearings are the most popular of all the ball bearing types because they are available in a wide variety of seal, shield and snap-ring arrangements. The bearing ring grooves are circular arcs made slightly larger than the radius of the ball. The balls make point contact with the raceways (elliptical contact when loaded). The inner ring shoulders are of equal height (as the outer ring shoulders). Deep Groove ball bearings can sustain radial, axial, or composite loads and because of simple design, this bearing type can be produced to provide both high-running accuracy and high-speed operation. Deep Groove ball bearings having an outside diameter less than 9 mm are known as Miniature ball bearings. Deep Groove ball bearings having an outside diameter => 9 mm and a bore diameter < 10 mm are known as Extra-small ball bearings. Standard ball retainers (cages) are made from pressed steel. Machined cages are used in bearing operating at very high speed or for large diameter bearings. Deep groove ball bearings with seals or shields are standardized. They contain proper amount of grease in advance.