These are bio-enclosures that are commonly used for microbiological analysis. These cabinets are suitable for Biosafety levels I to IV where samples being handled range from non-pathogenic to those with lethal effects.
The design of a Class III cabinet is gas tight. The welded metal cabinet construction is negatively pressured with a fail-safe mechanism for instances that physical containment is compromised. It can be ductless or ducted depending in the type analysis that will be performed inside the cabinet. The advantage of this type of cabinet is it provides absolute safety making it applicable for dealing with lethal biological hazards.