Of the maybe 10-15 different bottles I've used, I now will only buy the superpet.
I've replaced washers with 'hose washers', bought metal guards, and replaced chewed nozzles, but once you learn the 'trick' of the superpet, they cant be beat!
If, after you fill them, you turn them upside down, [installed position] and 'bounce' them off the heal of your hand, and see bubbles coming up - they're ready to hang on the cage!
I especially like the "double ball" concept to avoid backflow, and the stainless steel cap, so you could even hang it inside the cage! Mounting hardware is pretty good, too!
After reading members with problems posts, I E-mailed Superpet with the no-flo problem, recommending they at least give some directions, with no success.