This system is perfect for the monitoring and insuring healthy air quality for hoods using radioactive materials. There is one T connector with two critical orifices on each barb. The in line combination filter is used for stack discharge. The open face combination filter holder is used for worker breathing zone. Each system comes complete with 20’ of tygon tubing, 2 calibrated critical orifices, 2 combination filter holders, 1 box of a hundred (activated charcoal filter paper) and a vacuum pump. With the two calibrated critical orifices, there is no need for flow meters or differential gauges.