It's an RTA. I'm not going to try to babble endlessly about it. 24mm, Clamp style, three bottom feed airflow holes. Clamps span both sides of center mounted screw downs so no worries about direction of wind on the coil. Up to 3/3.5mm coils are fine. 5 or 6 wraps spaced span the air holes nicely. Thin the wicks a little. Not a real finicky deck. First build 2x26+32 fused parallel SS Clapton on a 3mm post gave me .23Ω. No leaking, no dry or even semi dry hits. Popped it on a scoundrel mech and it performs very nicely. Very good flavor, lots of fog. There are a lot of really nice single coil RTA's out right now and this one ranks with the best.