The LoRa Ra-02 is Ai-Thinker's long-range wireless module built on the Semtech SX1278 chip. It works in the 433 MHz band and can send small amounts of data over several kilometres in open space, up to 10 km with a good antenna. It needs no router or internet like Wi-Fi does; two modules talk to each other directly. It connects over SPI (NSS, SCK, MOSI, MISO, RST, DIO0) and runs on 3.3 V: do not connect it to 5 V, and use a level shifter on the signal pins with an Arduino Uno. It works directly with the ESP32 and the Raspberry Pi Pico. Never transmit without an antenna attached, as the module can be damaged. On Arduino the LoRa (Sandeep Mistry) or RadioLib library is used. It appears in projects such as remote garden sensors, mailbox notifiers and range tests.