Well then you do not have a KR808D-2
A KR808D-2 is a male battery with no atty at all. it is a 2-piece model. Male battery and female cartomizers.
I was looking at more pictures and I don;t know what the heck you have. If it is truly 8.5mm diameter i.e. less than 9mm, then it also is not any popular model. Is the atty really plain steel and the cart goes over it? Then it may be like Trio or the old Blu (not made anymore). If it is then you may actually be able to put a standard resistance 510 atty and 510 cart (or 510 standard resistance cartomizer like Boge) on the battery. Just be very careful if the cartos do work because you probably have auto batteries and if juice leaks on the end of the battery and gets in the hole it can damage or kill the battery. Real 510 manuals are seals on the threaded end and safe from that (but the autos are not safe from it). Even if 510 stuff fits your battery, you cannot put a real 510 battery in your charger. The type of model yours looks like usually has an opposite polarity charger which would melt a real 510 or cause a fire and vice versa.
May be worth giving up on it though and buying something from a reputable vendor.
Cignot,com, LiteCigUSA.net, Liberty-Flights.com