First I want to thank everyone who has added to this forum. There is so much information here it can make your head spin. However you guys and gals have helped me tremendously and I have narrowed my choice to 2 models. A 510 or an ego. My question is what is the diameter of each of these? From what I can tell the 510 is about the size of an analog but how much bigger is the ego? A Sharpie, highlighter,cigar? I don't want something too large but the battery life of the ego can't be beat. Again thanks to all for their input.