This is the hard drive adapter connector for the internal SATA 2.5" hard disk drive in the XPS 15 (9550 / 9560) and Precision 15 (5510) This piece is sometimes called an interposer.
Guaranteed Compatible Dell Laptops:
XPS 15 (9550)
XPS 15 (9560)
Precision 15 (5510)
DP/N: XDYGX, 0XDYGX
Alternate Part Numbers:
AAM00_HDD_CABLE
DC02C00BL00