I've used the SMC series extensively, and never had a problem with them leaking. http://www.colder.com/Products/Plast...x?ProductId=20

I buy them in bulk - approx $110 for 50 of each of SMF01 and SMM01

SMFD01 is a variation that has a check valve in the female coupling, costs a few bucks each.

You can also get them with different size barbs for larger airline, different plastic, etc.

I dont doubt that some people have had the o-rings leak for whatever reasons, but the only time I've personally seen one leak was when the owner let grit get inside the connectors, and the grit scratched the crap out of the o-ring.

Gordon