Please don’t confuse automotive light bulb 1004 and 1156 because they are all “BA15S”.

Automotive light bulb 1004 is litter bit smaller size than 1156 bulb.

Diameter of automotive light bulb 1004 is 19mm, but 1156 is about 26.5mm.

In additional, the wattage of automotive light bulb 1004 is also litter bit different with 1156.

1004 automotive light bulb is about 19w, but 1156 is 21w.

In order to make clearly what’s difference between 1004 and 1156, I will show you picture as below.

If you would like to get more information about automotive light bulb 1004, you can contact me at any time.