As far as I know the Npro (aka 2-n-1 as sold in 7-11) has always been RN4081 and RN4081 can be used either with atomizer and carts, or with cartomizers. Vaporkings.com has some blank cartomizers. AZSmokeFree.com has some RN4081 stuff in including a manual battery which I highly recommend over auto
batteries. NoSmokeVA.com has a very nice PCC that works with both RN4081 and 510, autos and manuals (I only use manuals).