The second level in the European E-carrier digital hierarchy. E-2 runs at 8.448 Mbps and comprises four E-1s at 2.048 Mbps each, plus 256 kbps of overhead and justification, or bit stuffing, to adjust for variations in the clocking rates of the incoming E-1s. Multiplexing is performed by M12 (Multiplex T1-to-T2) terminals that multiplex four E-1 signals, which yield 120 DS-0 channels at 64 kbps per channel for user payload. See also bit stuffing, digital hierarchy, DS-0, E-1, and E-carrier.