I know those guages can be convenient, but there is a potentially harmful issue with them you might want to consider. As the snake grows and gets heavier, eventually the guage won't support the snakes weight and it will pull off. Trust me from experience, it isn't a matter of if, it is a matter of when. When that does happen, if you are lucky the guage will simply fall in the tank with no problem. However, if you are unlucky, like the experience we had, the adhesive tape sticks to the snake and rips the skin/scales of the animal scarring it permanantly or worse. I would hate for you to learn the hard way.
I used to have a thermometer type with a plastic suction cup holding it on. Prec loved to hang on it. One day, luckily while I right there in front of the tank it came off, fell onto a skull in her tank and broke open...all the Mercury went everywhere! I quickly grabbed Prec out of there and cleaned out tank. So another hidden danger of those type!! I went around and took the rest out of the other tanks. Thank God I was standing right there.
LOL He is now known as Houdini I can't believe this little guy escaped Not one time but 2 he worked the top Metal screen and squeezed out through a gap, Lucky me I find him after a few hours. This is my last tank that has this sit on the top cover. Houdini has a Sweet but adventurous personality needless to say I sat some weight on all four corners now he's mad at me lol I will be picking up the New Cage this weekend at Petco.