If accurate temperature is needed, one is to have a temperature chromatogram as a reference, and the other is to measure it with a thermometer. (The temperature inside and outside the heating point is different)
It is incorrect to say that the place that needs to be corrected is red and the stress is released according to the distortion of deformation. This has nothing to do with the impermeability of red, and the node of pressure release and correction is also very important. In addition, some deformations can be corrected only by relaxing and tightening the stress without flame heating.
I think the price is okay. The ones I bought from Ou Shili cost more than a t