there are a lot of different RTA/RBTA styles. Most common is the kayfun style. Orchid's Lemo's Russians and many others fall into this category. This is where you build your own coil on the deck and it is covered with a chimney, then surrounded with a tank. basically, the suction from you hitting it creates the juice feed to the coils. This works much on a vacuum principal and works well. I enjoy my kayfun v4. Then you've got a genesis style RTA like the RSST which has the rebuildable coil part on top covered with a dome and a tank on bottom, a long wick either made ss mesh or Cotton or whatever that dips into the tank much like an oil lamp. Then you have things like the big dripper which is a normal rebuildable atomizer with a squonking style tank that sits on top and you press the drip tip down which forces juice through a small opening onto your cotton to feed the coils. This is only a brief explanation of just a few kinds. and its all about personal preferences. What are you used to/using now?