Amazon.com: BroadLink RM4 pro IR and RF Universal Remote, All in One Hub Code Learning Wi-Fi Remote Control for TV Air Conditioner STB Audio, Curtain Motor, Works with Alexa, Google Home, IFTTT :
PUSOKEI DC 12V 1 Channel 433.92MHz Wireless RF Remote Control Relay Switch,Wireless Relay Remote Control Light Momentary Switch Transmitter with Receiver for Home Use Industrial: Amazon.co.uk: DIY & Tools
Simple RF M4 Receiver - 315MHz Momentary Type : ID 1096 : $4.95 : Adafruit Industries, Unique & fun DIY electronics and kits