Essential Info The Illuminated Female DC Power Plug Connector is a great way to check the voltage and polarity of DC power supply connections for surveillance cameras, access control and other devices. One end of this 36 inch wire connector has stripped bare wire for a positive and negative hard-wired connection, while the other end has a female 2.1mm DC barrel plug with a built-in LED. The LED light will change color depending on the power being run to the stripped bare wire and out to the female DC barrel plug. If there is no power the LED will not be lit, if DC power is correct the LED will be blue, if DC power is incorrect the LED will be red and if AC power is present the LED will be purple. The LED light has a range of measuring form five to 30 volts AC or DC, an will shine brighter as voltage increases. The LED will remain illuminated so long as it is part of the connection so you can always see at a glance that your devices are receiving proper power. What's Included Illuminated Female DC Power Plug Connector