measures consistent with reality. I took one for testing. Results corresponding to other old and bulky equipment. I am now 4. When I put them side by side, I have a difference of 0.3 ° max on temperatures, and 1% maximum of humidity. Magnificent right ?. There behind a small flap to put up, or we can put on the wall. Dimensions (I had not found them during my 1st order): 10 cm width, height 8 cm, 1 cm thick. So neither too large nor too small. This is a button battery, I would have preferred one AAA battery for autonomy. But thickness + high. We will see in use. I'll probably buy more.