The right angle C13 connector positions the shaft of the cable flush with the back of the device you are connecting, saving space at the connection point.

StarTech.com 6 ft Cat 6 Black Molded RJ45 UTP Gigabit Cat6 Patch Cable - 6ft Patch Cord, 1.83 m, Black, 12.9 mm, 200 mm, 210 mm, RJ45 Male, RJ45 Male