IST’s Model IQ-250 is a single gas portable instrument which can be equipped with either a solid state, or elec-trochemical sensor. Any one of over 150 toxic and combustible gases can be chosen. A digital display indicates the gas concentration, and an alarm buzzer and alarm LED’s alert you to the presence of hazardous levels. The IQ-250 does not incorporate a sample pump, and samples by diffusion only. User adjustable setpoints are provided for low, mid, and high alarm levels. The unit operates on 4 ‘AA’ size alkaline or nicad batteries, or the AC adapter/charger. The IQ-250 weighs approximately 22 ounces, including batteries.