I'm wondering about what technique these use for their probes:

and do they have a place in electronics use.
They are about $1 now with free shipping, which definitely makes them as cheap as possible.
The data cited is below (some do come with batteries):
Features:
Modeling simple, elegant, LCD panels inline connections, moisture-resistant,
strong anti-interference, applies to refrigerated cabinets, display counters and
other needs of temperature measurement and display of various equipment.
Specification:
Temperature range: -50~ 110°C
Temperature display resolution: 0.1°C
Temperature measurement accuracy: 1°C
Long probe line: 1 meter molded case probe
Colour: black
Size: 47*28*14mm
Weight 22G
2 x LR44 button battery (Batteries not included)
Package Content:
1 x Digital LCD Thermometer without retail box
What it doesn't say is anything about the technology they're using to get the temperature measurements. What's inside of the probe? Is the accuracy an indication? Can they be used to measure some temperatures of e.g. LEDs or resistors similarly to thermocouple probes? Someone might have more information on these.
Obviously the 110 C range (if true) is somewhat limiting, but there are many things that could be measured within this range. As for any difference between multiple units, I assume these can be written down and then considered when taking measurements (they are probably difficult to adjust internally).