That’s a fairly common coil used in the Prime. And other Kayfuns for that matter.I love my Kayfun Prime. My coil preference for both kayfun lite 2020 and Prime is a simple 28gw kanthol round coil with a 2mm ID, 1.25 ohm, at 10 watts. The coil sits roughly 1.5 mm above the air hole.
I like to thin out the cotton slightly so it can absorb eliquid better. I also don't like stuffing the cotton down the juice wells so I use the open slots on the side to slide in the cotton in and make sure it's just touching the bottom on the juice wells.
Through testing I found the 2mm ID coil allows the air flow to hit the coil perfectly and move around the coil evenly. Because of this I was able to enjoy the subtle notes from my tobacco juices that I wasn't getting before from a 2.5 mm ID coil.
Even in long mode the flavor is outstanding.
Over all the Kayfun Prime is a solid tank. 10 out of 10.