Port plugs mount onto a port frame to cap unused ports to eliminate light from escaping. It allows a sphere or sphere system to be used for a variety of application configurations and cover the unused ports and prevent sphere from dust/contamination.
Portable air compressors typically use gasoline or diesel engines, instead of electric power. These are used to compress and direct the air for industrial applications. These are available in many different types that include reciprocating, rotary screw, and centrifugal. These are designed for direct-use applications such as sandblasting and spray painting.