I have the original 14500 Reo mini and all I use on it are 2 a7 full sizes. 510 to 510 adaptor or 510 to eGo adapter. I like the 510 to 510 best because its smaller and looks better. I cant wait to get an A7 mini for it though. I am hoping to someday order a larger Reo and a Reomizer2 or two, when I've got the money for it. But for now, I'm telling ya'll, the a7 atomizers do work, and they can work well when you get the hang of them. I'm sure the Reomizer2 is better in a few ways, but the a7 atomizers don't bother me at all. Once you learn how your wick/coil wants to be treated, it works well. Sometimes my wick/coil is oriented where it likes a longer, softer drag. Or sometimes it likes a faster, harder drag. It depends on where I orient the coil in the atomizer and if it is directly above the squonk/airhole or to the side. But the a7 does work well.