Please ensure that you make a clean straight cut on the pipe-tube to create a snuggle tight fit. It can be used for both beer/liquid and gas lines. However, do note that it is pressure rated for 100psi only (that is 3.3X your car tire pressure).
It is ideal for microbrewery, beer keezer, and kombucha setups.
Here are duotight Female Flare Fittings instructions on making the right connection and testing for leakage.
It is made from high-quality EPDM (Ethylene Propylene Rubber) which has excellent chemical resistance including being compatible with ozone, oils, a wide variety of alkaline and acid compounds, water, alcohol, ketone, and beverages. However, don’t use it with bleaches or undiluted chemical acids of 1pH or stronger. EPDM is BPA free. Unlike rubber and other PVC water purifier fittings, this is resistant to aging, weather and does not perish easily. Hence it is a nice attach and forget like of fitting.
Good quality, fits my purpose.
Inexpensive but good quality fittings from Kegland.