Product Advantages 1. Employ original imported high-precision sensor. 2. Four random gas sensors can be combined freely. 3. LCD dot matrix display, 4. Chinese and English operation. 5. The gas concentration unit PPM and mg/m3 can be shifted quickly. 6. The battery and voltage can be checked by one press. 7. One press to restore factory settings.Ultra-high buzzer alarm sound, alarm with sound, light and vibration at the same time. 8. Can record 100 sets alarm data, alarm record can b e checked on the device. 9. Data storage function, can record 100 thousand set data, historical data can be viewed on the device (optional function). 10. Rechargeable lithium polymer battery of large capacity, which ensure the device to work continuously for a long time. 11. Strong and upscale alligator clip, convenient to take along during operation. 12. Special engineering plastics housing of high intensity, strong and durable, exquisite and comfortable in touching. Specification Gas Detected 4 to 1 gas detection device(O2 H2S CO EX) Detection principle Electrochemistry and catalytic combustion Sampling Method defusion Measure Range CO: 0-1000ppm, H2S: 0-100ppm, O2: 0- 30%VOL, EX: 0-100%LEL Resolution CO: 1ppm, H2S: 0.1ppm, O2: 0.1%VOL, EX: 1%LEL Precision ≤± 2% -5% F.S. Data recording Storage capacity of over one hundred thousand sets. Interval time ranges from 10-3600seconds are settable.(Optional function) Response Time ≤10S Recovery Time ≤10S Repeatability ≤±1% Linearity error ≤±1% Zero shift ≤±1%(F.