SKF EXPLORER 6311 JEM RADIAL/DEEP GROOVE BALL BEARING ROUND BORE 55mm ID 120 OD
A nice touch is that the bearing is from SKF, a label that feels familiar to seasoned mechanics.
6311JEM SKF BEARING
SKF 6311JEM / 6311C3 / DEEP-GROOVE, RADIAL BALL BEARING / OPEN / C3 CLEARANCE / 55X120X29.