It will fit as far as the
threadings are concerned, but it might not
vape. Depends on the carto and the airholes. Not all kr8 cartos are exactly the same. I don't have a 901, but I have a 905 which uses 901 attys, and this is the issue with kr8 cartos. You can get an adapter for changing
threading to 510, and 510 cartos should work. Others might have different experiences with this.