SUKRAGRAHA Smoke Detector Board Module MQ-2 for Arduino Genuino System Used for Detecting Smoke, Flammable Gas (e.g. LPG, Methanol , Ethanol) by SnO2 Gas Sensitive Materials Dimension: 32 mm x 20 mm x 22mm Input Voltage: 5V DC Result: Digital DO: 0.1V / 5V [TTL Switch] with DO LED display; Analog AO: 0.1 to 0.3 V [ Higher Value Means Higher pollution ]