Rob, currently two different cartos available right now, to the best of my knowledge.
First are the boge. They have a hard (aluminum) body just like an atty, and on the mouth piece end there is a white hard plastic cap that is glued in place. They can be pryed out thoug. These have aluminum
threads.
Next variety is by SLB. They also have the hard body, but hasa soft rubber cap on the mouth piece end which are easy to remove. Great for refilling on the go. These are the most desirable ones.
Both varieties have a vinyl sticker, so to speak,wrapped around them. That being the case, they are a tight fit in the ego cone. But the SLB variety also come with a stainless finish without this vinyl which are great for the ego with cone. Or you can peel off the vinyl on either variety. Just need to remove the glue.
I have been using a drip tip on mine. These things work great. I top off easily
through the drip tip with about 5-7 drops when vapor and flavor drop off (maybe once per hour)
These 510 cartos work great.