KR-808, greencig, and 901s are all threaded the same. However, there are different issues with these three models that are all airflow related.
KR-808 airflow:
The battery of a KR-808 has holes drilled through the threads allowing air to flow from the side to the area between the threads and center button. The carto has groves milled into the center button. So in a stock 808 setup the air flows through the holes on the batt thread and then through the grooves on the carto button.
KR-808 carto to 901 battery:
1) Get the adapter from VaporCountry
2) use a staple mod to allow a gap between the batt and carto this still may not allow enough airflow, as the 901 batt threads don't have holes.
3) modify your 901 battery. Just use a dremel to carve a groove all the way across your battery (threads and button). This will allow the air to flow.
KR-808 carto to greencig battery:
Screw and go. No mod needed.
KR-808 carto to 510 battery
Get a 901 atty to 510 battery adapter from AltSmoke.com and use procedure 2 or 3 above. I think Altsmoke might be carrying KR-808 cartos to 510 batts adapters soon to.
Greencig carto to KR-808 battery
greencig cartos don't have the groove carved into the button. So you can staple mod it or carve the grove across the button on the 808 battery. Or you could groove all your greencig cartos (I chose to do the 808 batt).
Hope this helps some of the 808 (and greencig) owners out there.
Edit: Damn...I type too slow
