The ACK-I-m SASx 4-4SATAx 1-SB-0.5m R is an internal Mini Serial Attached SCSI x 4 (SFF-8087) to (4) x 1 Serial ATA (controller based) fan-out cable with SFF-8448 sideband signals. It measures 0.5 meter & is used for connecting a SATA/SAS controller (SFF-8087) to SATA disks, or a SATA/SAS backplane.