This is a time delay power off relay. Connect two devices; when one is powered off, the second device will be switched off by the relay after the selected amount of time. 

For example, it can be used with a bathroom fan; the fan would come on with the ceiling light and then turn off 5 minutes after the light has been turned off.

Name: Power Off Delay Module

Model: QF-RD21F

Voltage: AC 100V-220V

Output: The output voltage is the same as the input voltage, and the maximum power supply capacity is 10A

The device has four selectable time settings: (See image for settings)