The Microsemi Adaptec ACK-I-HDmSAS-4SATA-SB-.8M is an internal Mini Serial Attached SCSI HD x4 (SFF-8643) to (4) x1 Serial ATA (adapter based) fan-out cable with sideband signals (SFF-8448). It measures 0.8 meters and is used for connecting a SAS/SATA adapter to SATA disks or a SAS/SATA backplane.