These modules are made by the zillion....no manufacturer or data sheet
I have 5v versions and they work fine but I need to power the coil from a 12v source hence the 12v version.
If I power it from 5volts the red led illuminates not very brightly, the green led pulses with the digital pin high/low but the relay coil does not switch as not enough juice as 12v version on 5v supply.
Switch power to 12v and both leds remain illuminated
Take it away from the Arduino totally and power it from 12v to vcc and ground the red led (pwr) illuminates
Ground the "in" pin and the relay triggers and the green led illuminates
Wasted 3 hours on the blighter last night - think I will chuck it and it's 11 mates in the spares box and order a better board
Regards
Jonathan