I'll second the Igo-L, no floating positive post to short out your
mod, especially if its mechanical. I can drip about 10 drops from a 30ml bottle and vape that for quite a while depending my voltage. Another plus is it's short. The only negative i have with it is, since it is a push on cap intead of a thread on cap, the orings that hold the cap in place can get worn out after a while.
The phoenix
rba has a floating positive pin and can short out a mod if the positive post in the connector gets higher than the walls of the connector.