Characteristics of a Low Bending loss insensitive, Optimized for 1310 nm
Four classes are defined: 4 classes of fiber are defined in the latest ITU-T G.657:

• G. 657A1: these are G. 652D fibers with optically specified bending radius of 10 mm
• G. 657A2: these are G. 652D fibers with optically specified bending radius of 7.5 mm
• G. 657B2: these are not compliant to G. 652D, with optically specified bending radius of 7.5 mm
• G. 657B3: these are not compliant to G. 652D, with optically specified bending radius of 5 mm