Incandescent light bulbs
Traditionally, an tungsten incandescent light bulb has been the light source used in all of the various automotive signalling and marking lamps. Typically, bulbs of 21 to 27 watts, producing 280 to 570 lumens (22 to 45 mean spherical candlepower) are used for brake, turn, reversing and rear fog lamps, while bulbs of 4 to 10 W, producing 40 to 130 lm (3 to 10 mscp) are used for tail lamps, parking lamps, sidemarker lamps and side turn signal repeaters. These bulbs typically have either a metal bayonet base or a plastic or glass wedge base for the physical and electrical interface with the lamp socket.