LPD433 - Wikipedia
https://en.wikipedia.org/wiki/LPD433
LPD433 (low power device 433 MHz) is a UHF band in which license free communication devices are allowed to operate in some regions. The frequencies correspond with the ITU region 1 ISM band of 433.050 MHz to 434.790 MHz, and operation is limited to CEPT countries.
433 MHz RF Transmitter Module Pinout, Specifications, Equivalent...
https://components101.com/433-mhz-rf-transmitter-module
The 433MHz RF module is one of the cheap and easy to use modules for all wireless projects. These modules can be used only in pairs and only simplex communication is possible.
Insight Into How 433MHz RF Tx-Rx Modules Work & Interface with...
https://lastminuteengineers.com/433mhz-rf-wireless-arduino-tutorial/
Well, then 433MHz RF Transmitter and Receiver Modules are just for you! Hardware Overview. Let's have a closer look at the 433MHz RF Transmitter and Receiver Modules.