I believe the device has a bit of a design problem. The hex-shaped perforated opening on the top face looks to be the fan intake. Which, when clipped to your shirt in the desired manner, means that the intake is right up against your skin (either upper arm or chest). So IF it is able to get any airflow at all (if it isn’t totally blocked by your skin), it is close enough to be recirculating air that probably came from your overheated smelly pits or chest. Or, it’s probably sucking in your chest hair and yanking it out.
For $42, I would expect the air inlet to be located on the outer edge, or near the clip hinge. This isn’t worth $5.