I wouldn't use macroline with CO2... If you have compressed air, you'll be fine. I don't believe the connections on macroline will stand up that well to the freezing of CO2.

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I've never had a problem with CO2 on macroline. I wasn't shooting very fast(6 BPS or so on a mech cocker), but I didn't have any macroline problems.

the clear stuff is like aquarium tubing. I tried using it for my replacement banjo line and it didnt seal very well on the valve barbs. whereas, the fuel line seals on those barbs extremely well. (i had to cut it to get it off)

In the end, if you have access to the macroline, it will definately withstand the most amount of pressure. but if your in a pinch,
or need RT or QEV line replacement, try the fuel line.

UPDATE: Dont use fuel line, today I just blew a hole in it, it sounded like a gun going off! think it is ok to use for RT cabling, but not for main line cable.