If you want to use LED bulbs in your front turn signals or rear flashers, you are going to run into a problem. The original flasher unit used the resistance of the bulb filament as a way to see if your bulb is good or bad. If it is burnt out, you get the quick flash that tells you there is a problem. Because of this, when you switch to the LED bulb (which has no filament) it messes up the way the original flasher unit works. So now it won't flash! You have two choices. You can get some resistors, and do a bunch of soldering. Or you can buy this flasher unit, remove the old one, install the new one and you are good to go.