Originally Posted by smizak
I use the purple ones made for a 6.5 gal. acid carboy. The 5 gallon ones are orange. At least at my LHBS. I've never had trouble with them leaking, in fact, if it's below 60F those damn things will take your fingernails off trying to remove them.
I have several, and I thought they were great. Until I used them for wine in a 5 gallon carboy (orange cap). In less than 4 months, I had a slightly oxidized chokecherry wine in one carboy. It seemed to fit quite well, but apparently not as well as I thought!
So, I'd use them for beer and short term wines- but never again for a longer time!