Abstract: A portable test device for evaluating the effectiveness of different filtering media, preferably metallic filtering media, in removing particulates from the gas stream of an exhaust stack at temperatures between about 300.degree. F. and about 1500.degree. F., including a probe member insertable directly into the gas stream of the exhaust stack and a particulate filtering facility in which the metallic filtering media to be tested are positioned. Facilities are provided for the isokinetic sampling and passing of the sample stream withdrawn by the probe member from the probe member to and through the particulate filtering facility while maintaining the temperature thereof substantially at the temperature it had within the exhaust stack. Facilities are also provided which permit the metallic filtering media to be readily replaced by different metallic filtering media to permit comparisons of filtering effectiveness.