Do you really fiend that hard that you can't just wait til you're at a stoplight to drip? Takes 2 seconds with a unicorn bottle. I don't use tanks at all anymore just carry a 15ml unicorn bottle and drip all day. Don't want to squonk because you have to mod all your rda's for bottomfeed and then you can't use them on your other mods, I like to tinker with new mods too much to be stuck with one device but I have no issues dripping on the go. Get a unicorn bottle if you don't have one yet, 15ml is nice to carry its just like having a pen in your pocket, not really noticeable at all. Cheers
Threaded center post RDAs can easily be converted back and forth from bottom feed to top feed.