Correct, the connector cannot be sealed. Fortunately, there are not many attys with sealed connectors, so most any atomizer will work just fine, it doesn't specifically need to be for bottom-feeders. In fact, some types of bottom-feeder attys are NOT ideal for UFS. I have a couple of Vapage attys that due to their design I would be unable to close off the
juice, so they won't work in my UFS (though they do work well in Ody since it uses a different juice control mechanism)