Why is it seemingly impossible to get any measurements for the size of these things? lol I've searched and read and searched some more. Can anyone tell me either by measurement or by regular cigarette comparison, how long each of the above is, fully assembled with a carto? And, obviously the 501's would have the shortest duration and number of drags with a carto, but how does the KR8 stack up against the 902? What are the major differences between the KR8's and the 902's if any?