MQ135 MQ-135 Hazardous Gas Sensor Detection Module
	- Main chip: LM393,MQ-135 gas sensor 
- Dual signal output (analog output, and TTL level output) 
- High sensitivity and good selectivity for Sulfide, benzene, smoke and other harmful gases 
- Signal output indicator instructions 
- Size:36mm X24mm X25mm(L * W * H)