Went for a Short 150 mile ride yesterday
I wanted to report there was absolutely no noticeable increase in power fuel mileage or better handling
They just worked as they were intended

But on a serious note
They did assemble just fine
They thread very securely onto the wire just like the NGK
And have a positive engagement with the spark plug
They offer this 5K cap in 2 types with and with out the need for the spark plug nut
This one that I have needs the nut
PRO5U requires the nut
PRO5M requires the threaded stud (no nut)