This article tells you about the 3 main types of ecigs, which are also the main size groups.
http://www.e-cigarette-forum.com/forum/ecf-library/287787-three-main-types-ecig-explanation.html
The small models look like a regular cigarette, we call these minis or cigalikes. They are popular with new users because they look like a regular smoke (well - they do if you get a white one).
Bigger ones work better, as the battery is bigger: we call these mid-size or eGo-types. They are like a small cigar.
Bigger still are the APVs, also called mods, which can have big batteries for ultimate performance. They come in a box or fat tube style. Some have digital readouts or other extra features.
Recommended for your first purchase
We recommend a smaller mid-size model to start with, they are a good mix of size / cost / performance (performance improves with larger size, decreases with smaller size). So, a good choice is an eGo-type with a 650mAh battery and a clearo head.

--above, a mini is next to the smallest eGo type--
- centre-click the image, and it will open fullsize in a new tab
- or, right-click it, and choose Open in a New Tab (or window)
- it's a KR808 next to a Riva 650mAh
http://www.e-cigarette-forum.com/forum/ecf-library/287787-three-main-types-ecig-explanation.html
The small models look like a regular cigarette, we call these minis or cigalikes. They are popular with new users because they look like a regular smoke (well - they do if you get a white one).
Bigger ones work better, as the battery is bigger: we call these mid-size or eGo-types. They are like a small cigar.
Bigger still are the APVs, also called mods, which can have big batteries for ultimate performance. They come in a box or fat tube style. Some have digital readouts or other extra features.
Recommended for your first purchase
We recommend a smaller mid-size model to start with, they are a good mix of size / cost / performance (performance improves with larger size, decreases with smaller size). So, a good choice is an eGo-type with a 650mAh battery and a clearo head.

--above, a mini is next to the smallest eGo type--
- centre-click the image, and it will open fullsize in a new tab
- or, right-click it, and choose Open in a New Tab (or window)
- it's a KR808 next to a Riva 650mAh