Feature: With signal output instructions TTL output signal is low level Analog 0 ~ 5 v voltage output the higher the concentration the higher the voltage Color is show as pictures. PLS NOTE that due to lighting effects monitor's brightness / contrast settings etc there could be some slight differences in the color tone of the pictures and the actual item! Specification: Air Quality Sensor Module Condition: New Size: 32mm X22mm X27mm Main chip: MQ-135 Working voltage: DC 5v Package Included: 1 x Air Quality Sensor Module