Specifications Concentration: Low end: <1.0 parts per trillion <2 micrograms/cubic meter High End: 10 parts per million 20 grams/cubic meter Range: >1,000,000:1 Precision +/- 2% Primary Particle Size Range: 10 – 100 nm Precision +/- 2% of max. Specific Surface Area Soot Surface Area / Primary Particle Diameter