I purchased a new Recaro ‘Speed’ seat for the drivers side last year, for my track nc Miata. It turned out that these parts were not needed. Invoice further describes pertinent info, as do the instructions taped to the necessary parts. Fits both driver and passenger seat. The Cantrel Sportster CS slimline knob comes with the blank cap were sent from the Recaro factory for the Recaro ‘Speed’ seat (it also fits the Cross Sportster.)
The stock adjustment knobs that come on the RECARO Sportster CS are too bulky and won’t allow for the seat to fit in certain cars. This knob has a much lower profile, in turn allowing the seat to fit in a wider variety of vehicles. Also fits the RECARO Cross Sportster. 1/16″ allen wrench required to tighten knob down.