GeeekPi Raspberry Pi Expansion Board 4 Channel Relay Board Module Power Relay Module for Raspberry Pi 3/2 B & Raspberry Pi 3 Model B+ & Raspberry Pi 4 Model B(No programming required/Programmable) by Amazon.co.uk

• 4 Channel Relay Hat Board For Raspberry Pi is one of the "docker pi" module.Up to four layers can be stacked.It has 4 channel relay that you can put it on your smart home project. It also uses high-quality relay modules combined with the most popular microcontroller technology to communicate with the Raspberry Pi.

• Switch the I2C address of the device through the DIP switch on the circuit board to ensure that the four-layer module gets different addresses, thus avoiding the problem of address duplication.

• The relay module is very fast, easy to install, and supports multi-language development, making it ideal for smart home projects. It supports multiple modules stacked together for use.It can be accessed programmatically or directly by shell.

• WIKI:https://wiki.52pi.com/index.php/4_Channel_Relay_Hat_Board_For_Raspberry_Pi_SKU:_EP-0099

• Package includes: 1x 4 Channel Relay Hat Board, 4x M2.5x16 copper stick, 8x M2.5x12 screws, 1x Instructions