Hey KG...the AFS is basically a barrel/tank with o-rings that surrounds the atomizer/cartomizer and allows you to have about 4-6ml of juice in the tank. There is already a very small hole in the 901 atomizer and you drill a hole to use cartomizers and the hole is where the juice feeds from the tank into the atty/carto. It's kind of like an old-fashioned diving bell. The air pressure in the atty/carto is just enough to keep it from flooding, but as you draw and vape it pulls juice from the tank into the atty/carto and reprimes it..so it's constant/automatic dripping basically. There is also a Control Ring(CR) that you can use to adjust the airflow. It works extremely well!
As far as size and such...it's about the size of a 10ml bottle of juice sitting on top of your preferred battery...it does well on my Silver Bullet..and I've also just shelled-out for the GGTS to match it, so it will look really sleek and nice. I wouldn't suggest running it on a standard battery though and I don't know how it would look on a box mod..but any of the larger tube style mods it would look good with.
The reason why I'm so happy with it and also with the 18650 battery is that it finally solves the biggest nagging issue I've had with vaping vs smoking. With a pack of smokes...I never thought about it(not that this was a good thing)..I just did it. I do a lot of stuff that requires concentration and I could light up a smoke and never break my train of thought. With vaping I was having to stop, take my glasses off, find my tweezers, pull the stuffing, fill the cartridge, replace stuffing, clean up mess..try and vape..hopefully didn't flood it..etc..etc. And doing this every 20 minutes...I couldn't get anything else done. It was frustrating. I then found cartomizers and it was a bit better, but even then the whole refill routine was still required every 1-2hrs..and I had more trouble getting it right..just because there's less customization with cartos than atomizer/carts. I was chained to my desk full of e-cig parts and juice..or had to carry a huge kit if I dared venture out of the house.
Enter the GGAFSv2...I really can fill my AFS in the morning, pop in a fresh 18650 and just walk away from the e-cig table. When ever I want to take a hit..it's just there..no break in concentration. If I get a hit that seems weak..close CR..take a short draw(without firing battery..open CR and fire battery and vape. Once you learn how to work the CR..it's flawless..I can adjust air from completely closed off to full airflow, which in turn is also adjusting my juice flow too.
I now regularly vape all day with just this unit. If I'm going out to dinner or something, I'll check the tank and top it off before I leave, but I just don't carry anything else anymore. I don't need to. I've also been able to drop my nic level about 5mg's too..cause the vape is so consistent, that I need less nic to be satisfied. For me, it's the ultimate...yeah..it's not cheap..but it's solid as a rock..and I will be selling off my lesser gear soon, cause I just don't need it anymore..this is really all I need.