Provides additional volume for the air to drop suspended media. At the bottom of each vertical tube is a cleanout opening. The opening is to recover suspended media that has dropped.
When the trigger is pulled on the gun, the velocity out of the exhaust is faint at best.
It works really good.
I may fab up a box to install a filter and shop vac hook up. I'll make an inlet tube that cleans the window using incoming air flow.
If you don't use some type of sealer to seal the seam, it leaks like a ****.