Types of rda:
1:
This is the most common type:
- three posts in a line; the center post being the positive.
- side airflow: topcap with airflow holes.
2:
A multipositive design; you don't have to get your coils to share a positive contact point; you can secure each coil one at a time without disturbing the other coil.
2(b) the above example also illustrates another feature: the negative postpoints are part of the deck, and not something screwed/welded/pressfitted in afterwards.
3:
This is the abosolute rock bottom cheapest type of rda; positive centerpost and just 1 negative post.
Often available as a 14mm diameter, matching with standard eGo batteries.
4:
Glass!
There are a couple rda's that use glass so you can see the condition inside your rda.
4(b)
The above rda also features a chuff cap; intead of taking out the small drip tip, or the entire top part and end up disturbing your wicking, you can just take the topmost part off and look down inside your rda cylinder.
4(c)This example also features bottom entry airflow; that's something you will likely have with a glass rda, because you don't really want holes in the glass.
5: bottom air intake is susceptible to leaking; sometimes more so than side intake airflow;
so there have been a few top intake airflow rda's where air comes in from the top, to be guided down to the coil level where it then comes in sideways to the coil/s.
6: Something other than 3 posts in a line:
Here's one with bottom intake airflow; air comes up through the center post.
7:This one take air from top, and additionally has no center post sticking up. Only 2 posts separated widely.
8: There are a few rda's that can be used in hybrid to a mod of the right thread:
This one hybrids to M26x1 threaded mods.