8mm Speed Controller

If you put air through a valve and into a cylinder, the cylinder will operate at maximum speed. This is great for jump scares, or things you want to pop out of a box. But you may not know, they will retract equally as quickly - and in come cases, you might want that to be the case. However, if you wanted it to pop out slowly, or retract back in a more eerie manner,  then you need to control the speed at which the air goes through the cylinder! 
To do this, you need a speed controller. These allow you to vary the airflow from zero to full flow, allowing you a full range of control 
It is often best to add one to each direction (to both ports on the cylinder) after the valve so you can maximise your control. 
This is for a 8mm version of the speed controller