One model replaces the brake lamp itself, others are splice in. Red dye for your lenses is available. A wide variety of brake and tail and turn signal enhancements. All are spliced into wiring harness. Very good website with demos of each.
Makes turn signals into brake and running lights.
Higher priced model has a modulating function. Amber lenses brake and running may be illegal in your area. Most people used a combination of products. With the LED products aiming of the LED fixture is important because the light is a focused beam. If the fixture is not aimed just right then its effectiveness is significantly reduced.