Signal Dynamics BackOFF Brake Light Modulator Help those zoned-out drivers see you better! This compact solid-state electronic device converts an ordinary brake light into a high attention-grabbing alert signal when you are stopped or are stopping. When you apply your brakes, BackOFF will automatically flash your brake light three times, then hold it steady for 3-1/2 seconds Features: This signal is repeated as long as the brakes are applied This pattern is not random, it was selected for its ability to keep the attention of the drivers behind you Installs in minutes with two connections. Works with incandescent brake lights only, will not work with LED brake lights