This pass-through offers variable voltage output, the 4 stages out power output are 3v, 3.6v, 4.2v and 4.8v. Simply press the button 3 times in quick succession to cycle through the voltage settings. Cable length, 1.2 meters. You can turn off your device by simply pressing the button four times in a row.
The colours are as follows:
Blue light - 3 voltage output
Pink light - 3.6 voltage output
Red light - 4.2 voltage output
Green light - 4.8 voltage output
To use this device from a USB wall plug, the USB wall plug must be rated at least 2 amp. Ecig chargers only tend to come with 0.5 amp USB wall plugs these will not have enough power to drive the pass-through.