I started vaping on New Years day this year. I started out with the N-Joy N-Pro package and was fairly satisfied until the battery issues started. I found out, with a little research here, that the Smoke Stick batteries were compatible with with the N-Pro (RN 4081.) For whatever reason, these seem to be manufacturered better and last longer. I also tried the SS cartos, and while I didn't care for the flavor, they were re-fillable. They don't burn and one will last me over a month, even when I rinse them out with tap water and let them dry before re-filling! My questions are, is there a certain manufacturer that makes these for SS? Or are there any carto's that are comparable? I love these things!!