The RS 6661A-mSAS2 delivers robust RAID protection, high-performance data throughput, and mass-storage capability, via a single Thunderbolt™ 3 connection. 
 
RS6661A-mSAS2 key features:
Thunderbolt™ 3 to 2x Mini-SAS Ports (SFF-8088)
Cost-effective, high-speed, mass-storage RAID solution for Thunderbolt™ 3 Connectivity
Integrated RAID 0, 1, 5, 6, 10, 50 & JBOD Support
Directly supports up to 8x 6Gb/s SAS or SATA drives and up to 112TB of Storage Capacity
Works with any Thunderbolt™ 3 capable Mac or PC