Combustible Gas Detector detects dangerous levels of Natural Gas (Methane) and/or Propane gas. Features: Computerized calibration helps eliminate false alarms. Built-in self-diagnostics assures proper operation. Directly plugs into AC power. Uses about 6 watts of electricity. Samples air every 2 1/2 minutes. CG sensor alarm trip point: less than 25% of LEL (Lower Explosive Limit) of natural gas, propane and butane. UL 1484 Listed. Lock tab feature prevents tampering. Advanced surface mount circuitry increases reliability. Powerful 85dB Alarm. Five Year Limited Warranty. Dimensions: 4.7 inches x 3.1 inches x 2.1 inches Weight: 12 ounces.