Vapor4Life.com blanks are what I use for my KR808D-1 and they are definitely soft-cap for filling
But note - you have auto batteries. Self-filled and refilled cartomizers are more likely to occasionally leak vs prefills which are often lightly filled and well-settled. If a carto leaks it will leak right over the hole to the drag sensor, place most likely to damage or kill an auto battery. if you plan to refill cartos then I recommend you at least buy a spare battery, or even better a spare manual one (the manuals still have a hole int he threaded end but are harder to kill with juice leaks sinse they have no drag sensor right inside that hole)