The V2.5 fires down to 1.2ohms, has a beveled top, and needs an adapter for a Kabuki, and a trim ring.
The V2.5 also requires button top batteries.
The Classic fires down to .9ohms, has a flat top, a Kabuki will spin right on it, and will take flat top 18650's.
The P3 fires down to .5ohms, flat top, Kabuki ready, will take flat top batteries.
The Procyon fires down to .4ohms, flat top, Kabuki ready, flat top batteries.
The Radius fires down to .3ohms, flat top, Kabuki ready, flat top battery.