Features:1. Maximum/minimum hold feature for measuring absolute high/low peaks and hold datas.2. A great necessity tool to test H2S gas, perfect for using in biological medicine, fire detection and so on.3. When the concentration of H2S in the air exceeds the standard, sound and light alarm will be issued immediately, and the concentration value of carbon monoxide will be displayed.4. The product is ergonomically designed for easy handling and operation, perfect for household and working testing.5. In order to ensure longer battery life, you can set the timing switch machine, saving the time of manual switch machine.Specification: Item Type: H2S DetectorMaterial: ABSMeasurement Range: 0-100PPM: 0-0.01VOL%; 0-152Mg /m; 0-0.23LEL%Maximum Overload: 500PPMResponse Time: <30 secondsSensor Type: Electromagnetic H2S sensorAmbient Humidity: 15-90% RHBattery: 3 x 1.5V AA Battery (Not Included)Package List: 1 x H2S Detector1 x Instruction1 x Black Box