The REO Mini is a bottom fed juice feeder juice that runs on a 14500 protected battery and is fed by a 3ml bottle of the juice of your choice. It has a native 510 connection so you can use the atomizer of your choice. I use a 510LR atomizer or a 306LR atomizer. I have also used the 901LR with an adaptor and it works just as good as the 510 atomizers. This is a fully mechanical juice fed mod, meaning no wires or saudered connections to fail. Juice is fed to the atomizer by just pushing the bottle. Why do I like the REO Mini? I have owned a lot of mods and I was always looking for a Mod that had 3 things: 1. Good battery life. I get up to a full days vaping with one 14500. I was always caring chargers, spare ecig batteries or a PCC and that was a pain. Not sure why but I get better battery life out of my 14500s with the REO Mini than any other 14500 battery mod. Your battery life may differ depending on your vaping habits. I use a 900amH 14500 2. Carries its own juice. The REO Mini carries a 3ml bottle of my favorite juice, and feeds juice to the atomizer with just a push of the bottle. No messing around with carrying juice bottles and having them leak or trying to drip while driving. 3. Portable Pocket size and locking switch The REO Mini is approximately 3 1/8" tall at its tallest point (No Atomizer) Just under 1 ½" wide and only ¾ of an inch thick with a 510LR atty and Drip Tip and Atomizer installed its just over 4 ½ inches tall. The REO Mini has a locking switch. Just give it a ¼ turn and its locked. Another thing I will add with this mod being fully mechanical, the button does not have a rated life span. It should last for the life of the mod you would think. Rob's customer service is one of the best I have seen. He is here on the ECF most days to check in with people. I find him to be very informative and just an all around good guy. My story: I have been vaping for over 7 months and have been in search of my Holy Grail of Mods. I first found a Wood REO, the larger brother to the REO Mini and I fell in love with it. Then came the REO Mini. Now this is a work of art. Rob, from REOsMods www.reosmods.com, really out did himself on this one. You can find more on the REO Mini on the REO forum page. http://www.e-cigarette-forum.com/forum/e-cigarette-suppliers-forum/95123-reo-grand-opening-sale-255.html Rating 10+ all around could not be happier with my REO Mini.