Very simple ball and spring design and it does the job.
MBC Manual Turbo boost controller allows adjustments from 1 to 30psi by adjusting the bleed screws.
Anodised Alloy Body. 
 - Increasing boost pressure is often the most cost effective increase in horsepower.
 - Body Length: 55mm, Overall Length: 75mm
 - Easy Adjustment 
 - Lockable Once Set
 - Universal fits all turbo cars.
 
             
             
                   
                   
                   
                  