This document compares the specifications of three narcotics detectors. The detectors use ion mobility spectrometry (IMS) technology with corona discharge ionization. They can detect trace particles and vapors of narcotics and explosives in gaseous, fluid and solid samples. The detectors operate in both positive and negative modes between temperatures of -20 to 55 degrees Celsius. They have rechargeable lithium-ion batteries and analysis times of less than 10 seconds.