Basically you can use just about any carto with an ohm rating of about 2.8 and above. Do not try and use anything with LR(low resistance) or they will most likely short out within a split second or two. Another carto that I have tried at 6volts is the Nebula Turbo cartoz but you may have to use an adapter with your V3.
Hope this helps.
Aloha, Keith