PH-STAR manufactures Class II biosafety cabinets with two types, A2 and B2, Below you can find the Technical Specifications for of the two types.

Class II Type A2 Biological Safety Cabinets :
The Class II Type A2 biological safety cabinet is the most common Class II cabinet. It has a common plenum from which 30% of air is exhausted, and 70% is re-circulated to the work area.
It provides protection to the operator and the environment from exposure to biohazards and also protects products from contaminated room air and cross-contamination.
Note: If a trace amount of toxic chemicals are employed as an adjunct to microbiological processes, Type A cabinets should be exhaust-ducted.

Class II Type B2 Biological Safety Cabinets:
In a Class II Type B2 biological safety cabinet, all inflow, and downflow air is exhausted after HEPA filtration to the external environment without recirculation within the cabinet.
Type B2 cabinets are suitable for work with toxic chemicals employed as an adjunct to Microbiological processes under all circumstances since no re-circulation occurs.
In theory, Type B2 cabinets may be considered to be the safest of all Class II BSCs since the total exhaust feature acts as a fail-safe in the event that the down flow and/or exhaust HEPA filtration system cease to function normally.