Excellent.I'm using these to seal lines that are troublesome to seal, high pressure refrigerant lines. I hope they work. Much cheaper than the fancy blue ones from the hvac supplier. Sometimes the flare is scratched and today's r410a is a high pressure refrigerant that will leak past a scratch.wish me luck!It helped stop small gas leaks.Worked as expected. I was tired of dropping and searching for these when I changed lines.Good price. Fast shipping.Just getting into kegging. I put mfl swivel nuts to save time switching things, but none of those packages suggested using these. Now that I have them, so glad I got them. No more leaks!Keeps my gas lines sealed to prevent leaks as expected.Does a great job sealing beer lines from any leaks!