Time relays are widely used in amateur practice to obtain various effects, control models and processes. 
The included circuits allow a retention time of up to 30 seconds. 
The difference between the four schemes is in the accuracy of timekeeping. 
Power supply could be every voltage regulator with an output voltage of 9 to 12 Volts or battery. 
Overall dimensions PCB 65х42mm. 

This kit is disassembled, requires assembly and soldering. 

The appearance may differ from the one in the photo without changing the parameters of the product (This means that there may be a difference in the elements used (appearance, placement, color, shape or value)).