The build in the pic is a dual coil, 28g, 3mm ID, 0.5ohm (can't remember the wrap count, maybe 6).
Great vape at 25w!
3mm ID, is a very tight fit in the GM.
I've recently been building: dual coil, 2.5mm ID, 7wraps, 0.62ohms
Fantastic vape at 27-30w :)
Never leaks or dry hit