LabGard NU-427 is a Class II, Type B1 Biological Safety Cabinets that is used for work treated with minute quantities of volatile toxic chemicals and trace amounts of radionuclides required as an adjunct to microbiological studies if work is done in the direct exhausted portion of the cabinet, or if the chemicals or radionuclides will not interfere with the work when recirculated in the down flow air. The Type B1 Biological Safety Cabinet exhausts 70% of air through system HVAC systems while recirculating 30% of remaining air through HEPA filtration back through the work zone.