THERMO FISHER SCIENTIFIC's Model 445 opacity and dust-concentration monitor has built-in test functions, including automatic four-point linearity and optical surface-contamination checks. It measures the mass concentration of dust in stack effluents from industrial sites that require a continuous emission monitoring system. A durable pulsed LED serves as the light source, and an integral sighting device eases alignment of the sender/receiver and reflector units. www.thermofisher.com