G4 halogen bulbs are one of the most common bulbs found within interior lamps on boats. G4's are identified by the two small pins, 4mm apart, extending from a small glass capsule. G4 LEDs found on boats typically range from 5W to 15W. If you have a 20W halogen bulb on your boat it will get extremely hot and could be a fire hazard. Bulbs brighter than 20W are not G4's.

Care must be taken when selecting a G4 replacement LED for your boat. Most G4 lamps used on boats are ceiling mounted and use a G4 bulb that is horizontal, or parallel to the fixture. However, some bulkhead mounted "eyeball" lamps and bell-shaped reading lamps use a vertical bulb, where the bulb is perpendicular to the base of the fixture. Our Side-Pin (SP) type G4 LED bulbs replace the horizontal type, while our Back-Pin (BP) type G4's, or our MR11 LEDs, replace the vertical type.