Connect a 100GbE QSFP28 host interface to four SFP28 connections with a single direct-attach copper breakout assembly. AddOn 845418-B21-AO uses a QSFP28 connector at the host end and four SFP28 connectors at the breakout end, providing the physical interface transition required for 100GBASE-CU fan-out links. It is specified as compatible with HPE 845418-B21 and carries a TAA-compliant designation. This cable fits high-density Ethernet designs that need to distribute one QSFP28-side connection across four SFP28-side ports. Typical placements include server and storage uplinks, switch-to-switch aggregation links, and other rack-level network connections where fixed copper cabling is required between compatible interfaces. The direct-attach format keeps the connector assembly and copper cable together rather than requiring separate optical modules and fiber patching. The defining characteristic is its breakout topology: one QSFP28 end terminates into four SFP28 ends. That differs from straight-through direct-attach cabling, which maintains the same connector type at both ends. Buyers should verify that the intended equipment supports the required QSFP28-to-four-SFP28 breakout configuration and that the connector layout matches the target ports before installation.