Feature: 1. 1. Gas Measurement: The sensor preheats while the turning-on countdown. The refresh frequency is 1HZ. Do not charge in the process of measuring the flammable gas or explosion may occur. 2. 2. High/Low Alarm: 4 default values for high/low alarm with 4 forms of alarm and the alarm voice can be turned off. 3. 3. Data Record: Up to 1000 pieces of data recorded allowable. The default interval of data record is 5 seconds which can be set in the inL in the set mode. When the interval is set as 0 second the data record function fails. Delete operation will delete all the data recorded. 4. 4. Temperature Display: To set the unit as ℃ or ℉, default unit is ℃. 5. 5. Automatic Turning off: The unit turns off within 30 minutes if there is no further operation. Default turning on is this function. 6. 6. Battery Volume: If the volume is the last bar or less it is highly recommended to charge the unit. It is forbidden to activate the unit to operate lest the possible measure error or explosion. If the battery is low it may turn off automatically. Charging time: about 4 hours. Discharging time: about 8 hours. 7. 7. Calibration of 0 Point: It is recommended that the unit should be calibrated at the 0 point every month or if there is zero shift occurring to ensure the high accuracy of the measurement (please be sure that the battery volume is above 2 bars while calibration, and put the unit in the air for a while after turning on to ensure that the unit has its body temperature a little bit higher than the environmental temperature. 8. 8. Temperature Compensation: The data measured is compensated at the range of -20℃ to 50℃. 9. 9. MAX/MIN/Hold Reading: Press the button to calculate. 10. 10. Software Error: the unit\u0027s crash/turn-off indicates the mistake occurs in process of operation. Press the on/off button to activate the unit if it is forced shutdown by software. 11. 11. Compound Gas Monitor is widely used in petroleum, chemical, environmental protection, metallurgy, refining, gas transmission and distribution, biochemical medicine, agricultural research, etc. Specification: Specifications: Model: WT8812 Range: Combustible gas LEL: 0~100%LEL Oxygen O2: 0~30%VOL Hydrogen sulfide H2s: 0~100PPM CO: 0~1000PPM Resolution: Combustible gas LEL: 0.1%LEL Oxygen O2: 0.1%VOL Hydrogen sulfide H2s: 0.1PPM CO: 1PPM Accuracy: ≤±5%FS Response Time (90%): Less than 30 seconds Indication Mode: LCD displays real-time data and system state, LED, sound , vibration indication alarm Storage Conditions: Temperature: -10~55℃; Humidity: <85%RH Operation Conditions: Temperature : -20~50℃; Humidity: <95%RH non-condensing Working Voltage: DC3.7V (Li battery capacity 1800mAh) Charging Time: 4h Standby Time: More than 8h on end (slightly change with working state) Material: ABS Item Size: 153 * 71 * 49 mm / 6.02 * 2.79 * 1.93 inch Item Weight: 219g / 7.72oz . Package List: 1 x Compound Gas Detector (Contain Alligator Clips) 1 x Charging Cable 1 x Transparent Trachea 1 x Cover (With Screws) 1 x Carrying Box 1 x User Manual (English)