The Setra Systems 3301 & 3501 Series Particle Counter measures 0.3 μm to 25.0 μm through a long life laser diode and a flow rate of 0.1 CFM (2.83 LPM) with external vacuum source (by others) that pulls greater than >15” of Hg. Easy to configure and with user configurable alarm light, this stainless-steel particle counter monitors 4 user-selectable size channels to allow for continuous monitoring of particulates in your critical environment.