Tired of noisy shop vacs running all day during your air track experiments? We have a quieter air source solution. The air input port has three foam sound absorbers. The straight-through air path reduces pressure loss and unnecessary turbulence-resulting in a smoother glider operation. The square design allows the units to be stacked for convenient off-season storage-a real bonus if you are short of storeroom space. One air source can power two AP5615 Air Tracks! The air source comes with one air hose. If you want to power two air tracks at once, you will need an extra air hose (AP5743).