Dreffco 3/8 Inch x 18 Inch Non-Whistle Gas Flex Line for NG or LP Fire Pits and Fireplaces For Use Indoors or Out 3/8" Female Flared Fitting Each End. We've Included A 3/8" Female NPT & 1/2" Female NPT Fittings For Your Convenience 18" 3/8" Non-Whisle Flex Line is 3/8" OD and 1/4" ID x 15-5/8" Long w/o Fittings There Is a Staggered Pitch Every 2" to Eliminate Whistling Typicall Use Is for NG or LP Fireplaces and &lt;90K BTU Fire Pit Burners