HobbyKing sells radio control model aircraft, subsystems and parts. For quite some time, they sold dozens of models of transmitters, especially for video links and telemetry, that operated on unauthorized frequencies and at unauthorized power levels. They were also selling transmitters that had never received FCC approval. The FCC previously fined them $2.9 million for violating FCC rules and regulations. HobbyKing pulled the products and protested the fine, but the FCC noted, they did not dispute they had been actively marketing illegal transmitters – and the fine stands, due within 30 days.
Source: FCC Fines HobbyKing Nearly $3 Million for Marketing Unauthorized Drone Transmitters