EMI and RFI shielding includes coatings, gaskets, enclosures, sealants, resins and other products or materials that block out electromagnetic interference (EMI) and radio frequency (RF ...

The version of ESP8266 used in this project is the ESP-12, the newer, fancier model with RF shielding, a questionable FCC logo, and every single one of the GPIOs exposed on castellated connectors.

but with a licence to lose should they do that they are also a lot more careful about their RF emissions. Read the FCC statement and you’ll learn they are not trying to restrict the sale of ham ...