Below are our wiring adapters which can be added to any kit we sell. The relay with 50W resistor is recommend for new cars which you purchase Non-Bixenon HID kits for. If you purchase a Bi-xenon kit from us or Philips Bi-xenon kit in sizes 9004 9007 H13 or H4, you must purchase the 50W resistors to wire on the bi-xenon relay, since all bi-xenon come with a relay. Keep in mind, the 50W resistor is only for certains cars, and most do not need it. Dodge Ram, Ford F-Series 2006+, 2006+ Mustang, 2000+ BMW very much require them.