310 ECJ, or no suffix. Machined brass cages. There are several machined brass cage designs available for SKF single row cylindrical roller bearings: roller.
cylindrical roller bearings . . . . . . . . 656. 5.5 Sealed double row full complement cylindrical roller bearings . . . . . . . . 668. Other cylindrical roller bearings.
10 Sep 2012 BPW ECO Bearing Kit Installation Instructions - September 2012 Rev. 0. Page 1 of 4. INS-05. 1 Cherry Lane Laverton North, Vic. 3026.
For additional information about the meaning and limitations of the product data, refer to Single row cylindrical roller bearings and Principles of bearing selection