DW1 is a door and window alarm sensor. The door alarms can work with Sonoff RF Bridge 433. DW1 door alarm sensor detects the opening status and immediately sends alarm notification message to the app. 
PIR2 is a 433.92MHz RF PIR motion sensor that for human detection. The motion detector can work with the Sonoff RF Bridge 433, providing human detected alarm message push to your phone.
This RF Remote 433Mhz 4-Button is a Wireless 4 Buttons Push Cover Remote which control the learning code remote control wall switch, plug seat or extension socket. It's suitable for long distance and multiple switch control. The remote controller can be compatible with our W and N Series intelligent switch.
This RF Bridge 433 can convert most of the 433.92MHz RF Remotes into WiFi wireless. By adding the RF wireless Bridge to iOS/Android App eWeLink WiFi wirelessly, You can add up to four RM433 RF or alarms, also add them together (max. 4 devices). One remote controller can learn 4 devices, which means 16 devices supporting 433 MHz frequency can be added on the app through WiFi/2/3/4G network.