Although it is "only" Plastic (without functions) but lacking precisely this piece of plastic
for the consummate Mario Kart fun!
At first I thought there may be limitations of the sensor come since he with his left hand
but is covered this thought was after 5 minutes play already completely blown away.
(So far, no loss of signal strength or the like)
There are on the left rear side of the steering wheel, a "knob-extension" of the B buttons so that you
has to use a nice big switch at the rear. (Very comfortable)
It is a little smaller than expected, but is great in the hand and is very very easy.
Conclusion: A cheap but satisfying part and purpose for every Mario Kart lovers a "must have".