I use velcro on the glass right above the UTH, under the cage liner. Once you stick this velcro on, it does not come off with ease. I wrapped a peice of velcro around the base of the probe then stuck it on. I have a second probe that I can move around to double check temps such as directly on the UTH underneith the tank and the temp inside my warm hide. I am dying to get a helix though I gota find the extra money.