The boxes of mine say 510D and they usually have silver threads though I have one carto around that looks like Boge inside but has brass threads (I think it is a tan filter-look one but I would have to check at home). The 3 ohm ones are for slim ecigs. The 2 ohm ones are only for 450mah+ fat battery models and mods (which can also use the 3 ohm cooler ones). If you can ever find the Boge 2.5 ohm ones those would be the hottest to use on slim
batteries.
I love Boge. A bit slow to get that first fill in (tight stuffing) but I can usually get 10 days use out of a Boge with thin clear juices and sometimes longer.