Safe-T-Alert Propane Natural Gas Alarm, 120V Item Code SM-STA-40-411-120 Our Price $44.95 UL 1484. 85 dB alarm sounds at 25% below lower explosive level of propane, natural gas and butane. InteleCheck circuit: no false alarms. 65-inch cord. 120V AC. 5 yr. mfr.warranty. Made in USA.