New OEM Ford RH Rear 3nd Row Lower Seat Cover - the cover that came with the car when it was made!

2009-2010 Flex Limited Stone Grey  - perforated Diamond Pattern - 3rd row​

This fits late 2010-to 2012 also - the difference is this one has a seen stitch on the side and the later models do not - trivial but make sure you check photos - it is trivial. 

Right rear passenger side 3rd row Lower butt cover 

OEM # 8A8Z-7463804-CB