General Tools VOC08 Handheld VOC Meter with Datalogging makes approximate VOC (Volatile Organic Compound) measurements via a metal oxide semiconductor sensor versus the more expensive photo-ionization style meters. Unit detects ammonia, toluene, ethanol, hydrogen sulfide (H2S), and cigarette smoke. The VOC08 features the ability to store and recall up to 32,000 measurements, user-adjustable audible alarm, MIN/MAX recalls, a backlit dual line LCD, and more.