I wonder what the designation letters means in front/behind of the auto turn signal bulbs
Auto Zone has two bulbs 1157ALL for $5.47 Napa has bulbs 1157AVB for 69 cents Each.
Napa is a pretty cheap price.

Could just be their brand Number?
I always remember an 1156 is single element, and an 1157 is dual element(tail/stop).

Thank you