Review on Gain Express Temperature Hygrometer Psychrometer by Justin Cage

I bought this to get wet bulb readings for air conditioning cooling. The wet bulb temp is always fluctuating around 41-43 and I check in several places. I used another psychrometer and a wet-bulb thermocouple technique and the readings from this instrument were very different from the other two. The rest showed 67-68. I understand it's a few degrees difference, but 23-25 degrees is way too much. I checked the instructions and changed the batteries, but that didn't help. I think you get what you paid for. I would ditch it and buy a more reputable product.