Flush back indicator lamp approx 72mm rubber back, stainless steel rim with plastic or glass lens. uses a 21w - 44mm x 14mm festoon bulb . a useful lamp where additional lamps are required without the need to cut large holes. two mounting bolts to rear. offered with amber lens for indicator, red lens for rear or clear lens for side or reverse. For spare bulbs please see our B618 (6v) or B273 (12v).