I love my Cisco 306 atomizers on my REOs. The other advantage of the 306 on a REO is that the 306 holds less juice than a 510, so it is easy to keep the overflow well dry. On a bottom feeder, if you are going to put it in your purse or pocket, you always want to vape it before you set it aside, so that the atomizer doesn't release a lot of excess juice. In other words, don't fill the atomizer right before you put the pv in your pocket.