What is the SlimSAS 8i SFF-8654 to 4 X SFF-8639 NVMe U.2 Cable used for?

The SlimSAS 8i SFF-8654 to 4 x SFF-8639 NVMe U.2 Cable is used for connecting a host controller or HBA (Host Bus Adapter) with an SFF-8654 (SlimSAS 8i) connector to up to four NVMe U.2 (SFF-8639) SSDs.