I got those and tried using them. They are overly vague and don't adhere well to the motor. Especially if the only spot you have is finned. I ended up ripping them off on a couple of my motors as with the fan shroud/heat sink, the sticker was covering the only exposed aluminum I could point a temp gun at. Besides, having to take the body off to read them kind of made them pointless. If I can read it, I can just as easily get an accurate measurement with my temp gun.Today I noticed some temp stickers you can put on a motor, for example.
20 euros for three strips but nevertheless pretty cool.