Shown below is the MGA pneumatic turn signal switch assembly. It has a "D" shape threaded neck to orient it properly in the dash, and a knurled nut to retain it there, and a manual actuation lever which is mounted on a hexagonal shaft. When properly mounted the lever hangs straight down and is pressed to the right to actuate the right turn signal, and to the left to actuate the left turn signal. Inside it has a spring loaded piston with a leather cup which is moved towards the back when actuated. At the rear is a small set screw that can be adjusted to regulate the flow of air into the unit, such that the return speed of the piston can be regulated, thereby controlling the time allowed before the switch turns itself off. A reasonable time for the automatic turn-off may be about 20 seconds. All wiring terminals are located on the back of the unit.