Cylindrical roller bearings are manufactured by NTN Bower® in several series that differ in proportion, width, and load rating. Bore size for each series increases in multiples of five or more millimeters and for each bore size a selection of different narrow and wide series is available to meet the needs of most applications. External dimensions and tolerances conform to RBEC 1 metric bearing standards as defined in the American Bearing Manufacturers Association (ABMA) and American National Standards Institute (ANSI). NTN Bower® standard product lines include two basic series the M series for light and medium radial loads and the W series for heavy to extra heavy radial loads. Only complete bearing assemblies interchange between the Max-Pak and the M series bearings separable rings and roller assemblies do not. Bower® Cylindrical Roller Bearing, Series: M Series, 27.97 mm Bore Dia, 52 mm Outside Dia, 1 Row, 15 mm W, Open Closure, 31000 N, Hardened Alloy Steel Bearing, Composite Steel Cage, -40 to 120 °C