Data are presented on the wind tunnel performances of two prototype Inhalable Particulate Matter (IPM) inlets designed for use with a dichotomous sampler. One was developed at the Aerosol Science Laboratory (ASL) Colorado State University, while the other was developed in an independent effort at the University of Minnesota (UM) and Lawrence Berkeley Laboratory (LBL). The ASL inlet is based on a unique omnidirectional cyclone fractionator, described in detail. Over the range of wind speeds from 0.5 - 24 km/hr, its measured 50% cutpoint was virtually invariant, 14.4 - 13.7 micrometers--well within the presently proposed IPM 50% cutpoint requirement. The UMLBL inlet results indicated near compliance with the IPM performance envelope, but there remain some small differences in data generated by UM and ASL personnel. Enrichment is apparent for both inlets in the 1 - 10 micrometers particle size range at the highest wind speed.