The SKF 6311 is an open deep groove ball bearing (unsealed), featuring a 55mm inner diameter, 120mm outer diameter, and 29mm thickness. Made of high-carbon chromium steel (GCr15) with a pressed steel cage, it suits medium-high speed, heavy-load applications (e.g., large motors, mining machinery, machine tool spindles). It handles radial and bidirectional axial loads, offering high strength, low friction, and long service life.