Picture shows the T10 on top and T14 on bottom. I couldn't find any information on sizing for this. I first ordered the 10, but it was smaller than my original fan. I looked the opening under my fireplace and it looked like I had enough room to fit the 14 incher so I ordered that one - the idea being that it would push more air and I could run it at a lower speed. I'm happy with the purchase and it is much quieter than my old fan. I can run this at speed 7/10 and I don't feel like I need to adjust the volume of my TV to compensate. Airflow seems good, and I like the thermostat control. I used the included Velcro pads to mount mine to the back of my fireplace. They are plenty strong to hold it in place and even provide some vibration dampening.Cons:This could use some better instructions for mounting. For example, if I mount the temperature sensor in the cavity below the fireplace (as shown in the included booklet) and have a high temperature kick on the fan, then airflow increases in that cavity and instantly cools the sensor, causing the fan to turn off (even though the fireplace is still plenty hot). I ended up clamping the temp sensor in direct contact with the metal shield under my fireplace and the sensor read 35 degrees hotter than before. This is enough to keep the fan running when it needs to in order to distribute the heat.There are lots of wires and they are pretty long. The pictures in the ad make it look like you can easily hide the wires, but they stick out quite a couple of inches below the control pod. I just left my control pod out of sight so that the kids don't play with it. I set it to turn on when a high temperature is detected (something you can configure) and that is good enough for me.
Rating: [5 of 5 Stars!]