I have couple stuck to the walls but in winter they gave me false low readings picking up temps off the glass. I have couple with probles inside the hides, infrared gun, and couple of the kind Ed just posted here. The ones for 10$ each. Those I just position on the tank floor in the areas away from the walls. I must say I have pretty darn good idea of my temps. Humidity stays pretty much this same throughout the tankThank you Jockma, ZEROPILOT - Thank you. can I just lay them in an area or do they need to be mounted?