The nipples I use in the coke bottles including the tube was R21 and because I took every thing the guy had I got them at R16 each. Honestly cant remember what brand it is, but they do not have the ball bearing, and they do not work on the plastic bottles only on glass, as they cause a suction and the sides of the bottle give in causing the system too flood. Only too be used with glass bottles, which is very heavy.
My one tub has a bunny feeder and it works well, they haven't tried to chow it yet. It was a second hand one I got for free because the pet shop owner did not have enough for me so he gave me the last one for free.
I'm setting up my rat racks for larger scale breeding next month, and will experiment more until I find a system that works perfectly for me. I also did get some videos on you tube on how to build watering systems, its more useful than just the picture instructions as you can see how it works now. l