Flight Structures made door 3 overhead crewrests for the 777 before Boeing introduced their product. BA
was the launch customer, followed by NG
IMHO - I think it's a better product, but it is hard to adapt it to the revised center bin support structure present on new 777. Boeing's other advantange is that it is line-fit on the assemble line instead of the extra 3-6 weeks it takes to retrofit the Flight Structures crewrest.
Of course, you could use the lower deck crewrest (Flight Structures made those for Boeing), but what for, the take up valuable cargo space, are smaller and are less comfortable.