Long story in short, it’s a 5V wifi inching/selflock relay module by SONOFF.

Just like a standard SONOFF switch, you can use it to work with eWelink app, Amazon Alexa, Google Home, IFTTT..etc.

The 5VDC input, nano size and dry-contact output makes it different from traditional SONOFF product, this product is a wireless switch supports inching /self-locking mode. Users can add the device to the APP eWeLink in order to remotely control connected home appliances or devices. In self-locking mode, customers can remotely turn on/off connected devices immediately.