Primary Filament Operation at 12.8 Volts

• The primary filament is used for normal marker-lamp (the rear light that comes on when you turn on your headlights) operation. The 1157 lamp can sustain 2.10 amps at 12.8 volts, and will last an average of 1,200 hours. The 1034 lamp can handle 1.80 amps at this voltage, and will last an average of 200 hours.
  
  

Secondary Filament Operation at 14 Volts

• The secondary filament is used for turn signal operations. The 1157 lamp can sustain 590 milliamps of electrical current at 14 volts, and lasts an average of 3,000 hours. The 1034 lamp lasts an average of 5,000 hours under these conditions.
  
  

Considerations When Choosing Which to Install

• Since both lamps are used as combination turn-signal and marker lamps, choose the lamp that suits your needs best. If you do a lot of daytime driving and require a long-lasting signal lamp, install the 1034 lamp. If you do a lot of nighttime driving, and do not need to use your turn signals often, choose the 1157 lamp.