1. size: 32mmX22mmX27mm 2. Chip: LM393, ZYMQ-2 gas sensors 3. Working voltage: DC 5V 4. characteristics: 1>. with a signal output instruction. 2>. dual signal output (analog output, and TTL level output) 3>. TTL output 4>. 0~5V analog output voltage, the higher the concentration the higher the voltage. 5>. the gas, natural gas, city gas, smoke better sensitivity. 6>. with a long service life and reliable stability 7>. rapid response and recovery characteristics.