SetTransmitPower I can't access the apk but I'm pretty sure it is another hidden test app not meant to be used by end-user Given its name it could be used to adjust the transmit power of the cell phone antennas SAR = Specific Absorption Rate (https://en.wikipedia.org/wiki/Specific_absorption_rate) XDA users removed this without any issues. To be 100% sure it would be good to test the SAR without this package (just in case)
Phones target this application