Ok, I just went down to my local smoke shop and decided to give this e-cig thing a try. All they had was a brand called sinless smoke so that's what I got. Now, as I look at all the info and sites related to e-cigs, I notice that all the other brands and types seem to have a model number associated with them, like 901, 403, 501, etc... There are no numbers anywhere on mine and nobody seems to include it when they are comparing all the different types and brands. Does this mean I can only buy cartridges from sinless smoke? When someone talks about modding a (insert model number here), how do I know if it applies to my sinless smoke e-cig? Where does my e-cig fit into all of this? Can someone shed some light on this for me?