The speed brake lever is located on the left side of the pedestal. It has two positions – IN and OUT. This is accurate to the real aircraft, which only has IN and OUT positions. 

The speed brakes do have a ‘blow back’ feature that varies their maximum extension angle based on airspeed. The speedbrake extension angle at high speed is less than the extension angle at low speed. This difference in extension angles is to ensure that the speed brakes provide a constant deceleration rate across the entire speed envelope.