Needed to prevent brake light BCM trouble codes when removing center tail lights on CAN-bus equipped models such as 2011 to present Softail, 2012 thru 2017 Dyna, 2014 to present Sportster and 2014 to present Touring. Transfers running light and brake light functions to turn signals and maintains turn signal function. Not suitable for bikes that came with rear triple-function lights from the factory.