Very easy to throw in a large single coil or a couple of them, despite the post holes not being drilled all the way through. The removable top cap bit has punch outs for dual or single air flow in it, though with a single coil it seems to work better with a centered coil and air from both sides still. The top cap as a whole isn't notched making it easy t o rotate it to center the air flow on the coils no matter how you have the air restricted, though it does make it a little harder to remove the RDA from a mod.

I had to take a file to some of the edges, like the edge above the drip tip o-ring, to save my fingers and the o-rings on some of the 810 tips I wanted to try in it.