RPi Relay Board (B) – 8-Ch Relays Expansion Board for Raspberry Pi. Control high voltage products using your Raspberry Pi. Supports Raspberry Pi A+/B+/2B/3B/3B+. High-quality relays load up to 5A 250V AC or 5A 30V DC. Photocoupling isolation for interference prevention. Standard rail mount bottom case. Onboard LEDs for indicating relay status. Relay control pin selection jumper for custom pin control. Reserved control interface for working with controllers like PLC. Development resources and examples included.

Features

Supports Raspberry Pi A+/B+/2B/3B/3B+
High-quality relays load up to 5A 250V AC or 5A 30V DC
Photocoupling isolation, prevent interference from high voltage circuit
Standard rail mount bottom case
Onboard LEDs for indicating relays status
Relay control pin selection jumper allows controlling the relays by custom pins other than the default pins
Reserved control Interface, allows working with controllers like PLC
Comes with development resources, including examples in wiringPi, bcm2835, python, python-bottle (webpage control), and crontab (cron job)

Resources
Waveshare Wiki

Dimension