This item is currently out of stock.
When you're mounting a round 4-inch trailer light, the grommet is what fills the gap between the light housing and the sheet metal or fiberglass it's mounted through. This one is sized for a 4-inch nominal outside diameter with a 4.5-inch inside opening to accept the light body.
Pair it with your 4-inch round marker, stop, turn, or tail light for a finished, weather-resistant mount.
