49 models in the 634 series, 4–4 mm bore. Every row links to the full specification page and to the cross-reference page of that model.
634 series bearings follow the ISO dimension plan for this family, so a given number is dimensionally interchangeable between brands - see the cross-reference to confirm. Choose the suffix for your duty: shields for dry, clean positions, contact seals for wet or dusty ones, and a larger clearance class where the fit or temperature demands it.
Other Deep Groove Ball Bearings series: 62 · 60 · 63 · 618 · 619 · 69 · 68 · 160