A previous technical directive gave teams further scope to add supportive skids, also known as satellite skids, on the plank further away from the four measuring points.
Those support skids were understood to be legal as long as they had the same vertical stiffness as the main skids, but they didn't reference thickness.
In recent weeks some teams, including Ferrari but not Red Bull's other rival McLaren, were deemed to have taken advantage of the provision to go beyond what is intended and come up with thicker protections that help protect the main skids.
The FIA accepted Red Bull's argument that Ferrari and some other teams are exploiting a loophole in the rules. Rather than wait until Qatar to give teams more time to react, it therefore issued a technical directive that is active with immediate effect, starting from this weekend's Las Vegas Grand Prix.
The directive effectively takes out the reference allowing these additional protective skids, which means teams will likely have to take extra margin with their ride heights to reduce the risk of exceeding the 1mm of plank wear allowance.
https://www.motorsport.com/f1/news/fia- ... /10674832/