That's an estimated power range that's the coils are supposed to perform at. Which sounds about right for that resistance; I fire single .6Ω coils at 25-30w, and dual coils reading .6Ω at 30-40w. Best to start at the lower end of the range, see how it works then slowly increase as necessary. You don't *need* to run at any particular level other than that satisfies you and is safe.