HDHalo Technology. These HD LED halo rings have been designed from the ground-up to be absolutely the brightest, most reliable halos physically possible. Each halo is populated with a large number of high-density (HD) LEDs, which are then coated by a diffusing gel, resulting in a perfectly uniform light when turned on. When off, the diffusing gel hides the chips, resulting in a clean, OEM appearance.
Sizing: All sizes are listed by outside diameter, in millimeters. Width is 8mm, so inside diameter is 16mm less than outside diameter. Total height is 4.5mm.
Inner Shroud: 130mm
Outer Shroud: 100mm
Wiring: All wires have a durable braided wire covering. The LED has a 20-inch wire with female JST type connector. This connector may be de-pinned in order to run wires through small holes during installation. Both the input and output wire on the driver are also 20 inches each. A pigtail is included that is also 20 inches, with male spade connectors on the end to connect to factory wiring with included T-taps. You will have plenty of room to run wires anywhere you'd like.
PWM Control: Aside from the high brightness and perfectly uniform output, one great feature of these halos is the integrated multifunction PWM dimming control. The drivers have four wires, to be connected to any 12V signals as follows:
White: White Low Power, 50% brightness
Red: White High Power, 100% brightness
Yellow: Amber Signal, double brightness, flashing (dims if powered more than two seconds)
All input wires activate the halos, at different brightness levels. All switchback halos ship with "low" priority drivers. This means that if both "low" and "high" power inputs are powered, the LED will light up in white, with low power level. This is convenient for connecting the red wire to a parking light or DRL signal, for use during the day as a high-power DRL. Then, if the white wire is connected to the headlamp power, they will dim down at night. If the yellow wire is powered at any time, the halo will light up in amber color, intended for signaling. If you'd like to use amber all the time, no problem! It will dim automatically if powered for more than two seconds, to keep it safe.
This entire setup allows you to connect the halo directly as a multifunction lamp, without any external controllers needed. Of course, this is completely optional. You can just use one or two of the input wires if you'd like.
NOTE: These halos are not compatible with the E46 M3 non-facelift shrouds.