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The problem is plastic, the electronics should be fine til 100°C (212°F), plastic only till 50-70°C (122-158°F).
While running: 70-80°C (158-176°F)
Yes, I have forgotten that.
USB Sticks are even lower quality. What have I heard: The hierarchy of flash chips, from highest to lowest quality: SSD > SD > USB
Didn't know about these, but if it works it works