Sealed, 4 in round stop, turn and taillight may be used on both curbside and roadside of vehicle or trailer. Fully automated manufacturing process ensures consistent quality and reliability. Features extra wide, spin-welded, tongue-and-groove lens lip and waterproof seal. High performance, copper alloy conductors eliminate the possibility of wire failure. State-of-the art bulb design features three supports for the minor filament and two supports for the major filament providing long bulb life. Wedge-base socket prevents premature bulb failure. Includes light, grommet and 431-491 straight plug. 4-1/4 in Dia.