1, 4 Channel SPDT(Single Pole Double Throw) 10Amp power relays. It can be easily connect with Raspberry Pi or Arduino, or other IoT projects, or home automation control application.
2, Darlington transistor circuits drive relay coil. LED indicators for power supply and each relay action. 
3, ABS plastic enclosure, you can use screw mount to wood board or wall, of course, can also be placed on the desktop. 
4, High quality screw terminal block. Pitch 5.0mm/0.197". Wire range 26AWG ~ 12AWG / 2.5mm square.
5, Operating voltage / current: DC 24V / 70mA.

Datasheet: https://www.czh-labs.com/tmp/madeimg/datasheet/f-1002.pdf