I received this after having a severe whistling issue with my TP04. This model is actually a significant downgrade compared to that model. They advertise that the new model is quieter, but in actuality all they did was massively limit the max fan speed. On Max fan speed, the amount of air being pushed out is close to half of what the TP04 was able to produce.Additionally, the NO2 sensor on my unit is completely defective. It never registers any NO2, even when my other air quality sensors detect very high amounts. It has never once registered NO2 above zero. Overall, I'm disappointed with this supposed upgrade. They need to go back to the drawing board and realize air flow is more important than pretending that your product is quieter.