Flasher relays are simple relays which are based on time rather than load to maintain a blinking cycle for your car, truck, or motorcycle. If you think about it, adding resistors increases load, so if you add LED bulbs as well, the two are basically neutral, so the blinking rate is the same. If you don't want to add resistors, replacing the flasher relay with an electronic relay is constant regardless of LED bulbs, incandescent, resistors, etc., making for a much cleaner and safer installation. Alternately, and more traditionally, when you replace an incandescent signal bulb with a new high-power LED turn signal bulb, the lower current draw means the bulb blinks faster, so a high quality load resistor is required. Don't use cheap gold 50w resistors, which most certainly will fail very fast. Instead, high quality Morimoto HD Load resistors will not heat up nearly as hot, but will provide the same blinking rate as stock. Inside the quality load resistors, there is a proprietary solderless design, ensuring failure is almost eliminated entirely. Want the best? Choose Morimoto or Profile with The Retrofit Source.