The Model C is a highly sensitive hydrocarbon detector. The Model C is a non-calibrated detector that is used primarily for arson investigation to detect trace amounts of hydrocarbons. With its simple operation, the Model C can detect combustible hydrocarbon concentrations of less then 200 parts per million. Model C+: Similar to the Model C, the Model C+ is a highly sensitive hydrocarbon detector that is also used to determine if a gas is explosive, and will only annunciate if the gas has exceeded the preset level of 10% of the LEL (test gas is methane). The Model C+ may also be calibrated to detect other gases and combustible hydrocarbons with concentrations of less than 200 parts per million. Model 850 Investigator`s Aid: The Model 850 Investigator`s Aid is a rugged, non-calibrated detector which detects the presence of hydrocarbons/accelerants/gases that may be present at a fire scene. It is equally effective as a general purpose gas detector. It incorporates advanced signal processing techniques which make it one of the most effective and reliable survey tools available. In addition to its uses in the arson investigation field, the Model 850 is an excellent tool for use in detecting Methane Outgassing (landfills), Leaking Underground Storage Tanks, Hazardous Materials and Petrochemicals.