I purchased the FB400 a couple months ago because I was having difficulty maintaining a constant temperature in my Kamado Joe. Yes I am a newby to smoking, but I have been grilling a long time. I recently wanted to start smoking and after hearing the nightmares my friends have gone through I decided that I was going to find an easier way to smoke meats.In my research and experience I have found there are several factors to why a kamado has variations in temperature. The vents are the only way to set a temperature, but the temperature can change because of the size of the fuel (lump charcoal is not the same size. A bunch of small pieces have more surface area than one large so the temp can go up and vice versa), changes in air flow and how the fuel is placed. I have found the FB400 does an excellent job in keeping the temperature constant because it manages the air flow.Once you get the FB400 app and connect the device it is a very simple process. You start the fire and leave the lid open until you get about 60 degrees below your target temp. Close the lid and the top vent until it is barely open. Attach the FB to the lower vent and make sure there are no gaps for air to get around the FB400 and its adapter. Plug in the FB400 and set the temperature then wait. It is that simple.It works by restricting the air flow so the FB400 is the only way the fuel can get air. Once the grill reaches the target temp the FB400 will maintain it within a few degrees. Understand the oven in your house does the same process of keeping the temperature within an established range.Critical points:1. Make sure the FB400 has a connection to the wifi before you start your cook2. The location of the grill probe is critical. I purchased clips to attach the probe above the grill, because the temperature was a false high reading when attached directly to the grill and moving it will change the reading it gets.Pro:1. The FB400 keeps the temperature within a few degrees of target.2. You will get messages about the status of the temperature should it go above or below the alarm threshold with a suggestion of what you should do to correct the problem3. You will get a message when the temperature goes back within the threshold of the alarm.4. The software will graph the temp of the grill, the temp of the food and how much speed (percentage) the fan is using.5. The information for each cook is recorded and can be shared.6. You can also include notes in each cook7. Device works as a stand alone device, through the local network only, and if it has internet through the wifi it can notify your phone while your away. (Why anyone would leave their grill unattended is beyond me, but hey. Different strokes for different folks)8. The FB400 senses when the grill has been opened (you will get a notification) and it will wait 2 minutes before starting the fan (if needed) to get it back to temperature to avoid overshooting the set temperature.Cons:1. Probe location is critical and using tin foil to keep in the grill didn't work too well. (Buy a probe clip. You will be happy you did)2. Make sure the FB400 works before starting your cook to make sure you can connect. (The software has been updated to allow you to connect through the local wifi if the servers are down or to connect directly)3. The software does not tell you when it has lost connectivity so you have to go to a different screen and then back to make sure it is connected. ( Should be a minor fix for the software)4. Some issues with logging into the account sometimes. (My second cook took me 30 minutes to get connected for some unknown reason and then it worked. I have not had a problem since)Pro/Con (debatable): The unit is all one piece which makes it small, light and inexpensive. I have read some people voice concerns about what ifs and they are valid. But if you are that worried about a failure and replacing the unit then purchase some other model that is modular and takes up far more space. Remember, you not just paying for the hardware. It comes with software too, and that is where it either works or doesn't. (this little guy works)I am very happy with my purchase and it has been fun watching some of my friends marvel over how well the kamado and FB400 work together. After hearing their stories, I am pretty sure they will be ordering an FB400 for themselves.