In-stock 901 cartos are harder to find
Note - you can use KR808D-1/Vapor4Life cartos but even though they are the same
threading you do need an adapter to provide the battery connection air intake notches for most of them because the 900 expects the atomizer to have its own air intake hole. The adapter is called 901 to 808 (or 901 to KR808D-1)
Somebody did find some 901 cartos in stock and I mailed myself the location - let me get it...
OK - someone said they got 901 cartos here
http://www.ivape.net/shop/