I am using this in the 7gal X3 uni conical. A couple of notes: This sticks up fairly high in the conical so temperature probe placement is critical to maintain proper liquid temperature. The TC ports in the cone of the conical are too low and give you a falsely low reading. The temperatures in the upper part of the tank will be much higher. You need to insert a thermowell into the top of the tank and keep it fairly high in the liquid. This is a different mindset than using the external stick-on heaters that attach to the cone. Also 125 watts is probably a little too high for this size conical and the temperature tends to overshoot a bit. Again probe placement is key or using PID control would help as well. The controllers in the Icemaster chiller do not have PID (but they do control heat if you add the wiring) so I went with an external variac from Amazon to drop the thermal output down to about 50 watts. Bigger fermenters or cooler locations probably won't have this problem. The other mild annoyance is that the TC port to insert this thing angles down and traps crud so you have to be diligent about cleaning between brews. Overall I like it though because you can take everything apart to clean and you don't have electrical components stuck to the bottom of the fermenter while you are scrubbing it down.