Specifications include, but are not limited to: . Scanning electrical mobility sizing system (Brechtel, model Aerosol Products SEMS 2100 or equivalent) a) Broadest available particle size range - select up to 2 micron diameter b) Recirculating DMA sheath flow eliminates external pumps c) Fast CPC response and DMA scan times down to a few seconds d) Precise volumetric airflow measurement with laminar flow elements e) Compatibility with low pressure package for aircraft & other low pressure applications f) Easy to use software displays Number, Area & Volume size distributions g) Fully automated, long-term unattended operation h) Dry sizing package for low relative humidity operation i) High voltage design practically eliminates arcing problems j) Monodisperse particle selection and scanning software with inversion k) Real-time temperature, relative humidity and pressure measurements l) Includes sample excess flow option m) Modular design which is compatible with the Brechtel model 3100 HTDMA 2. Differential Mobility Analyzer (Brechtel, model Aerosol Products SEMSDMA-UG or equivalent) a) Allows for 0.01 to 2 micrometers diameter size selection at a maximum voltage of no more than 6000 volts. b) Easy disassemble for cleaning of the interior with no fine nylon mesh in the flow stream. 3. Drying Size Package (Brechtel, model Aerosol Products SEMS-DrySize or equivalent) a) Allows for dry sizing, for SEMS 110-230V b) Employs a coil of nafion tubing in a vacuum for minimal particle loses