Factory nuts needed replacing. They use a 21mm socket versus the factory 19mm sockets, but for the F-Type this isn't a problem at all - my 21mm socket is slightly wider than my 19mm socket (as expected ), but the aperture does not interfere. .These are proper flat nuts with washers. You look great, you work. Can't comment on durability yet as it's only been a few weeks. However very satisfied. There are no problems with missing threads in my set.