Philips H4 Heavy Duty Relay Wiring Kit for Car HeadlightsPhilips H4 Heavy Duty Relay Wiring Kit The Philips H4 Heavy Duty Relay Wiring Kit is a complete wiring solution specially designed for cars using H4 dual filament headlight bulbs. Unlike a single relay with connector, this is a full wiring kit that includes everything needed to upgrade both left and right H4 headlights in one package. It bypasses the factory H4 wiring completely and draws full power directly from the battery delivering maximum