What is the difference between 3157A and 3157na?
What is a 4157 bulb used for?
The 3157 is a dual contact (d.c.) bulb (Conventional 3157 Led Bulb shown left). The dual contacts are connected to 2 separate circuits inside the bulb. One circuit is for bright or high beam (braking/turn signals) and one for dim or low beam (running/parking lights).
The Krypton gas provides for a slightly brighter, and slightly bluish, light. So yes, you can replace a 3157K with a 3157LL, but no, they’re not identical.
Kenny, yes, these standard 3157 brilliant red LED bulbs will fit 4057K. The 3157 bulbs will replace many size bulbs such as 3156, 3057, 3056, 4157, 3157K etc. And there isn’t somethig different between 4057 and 4057k, just the named method is different.
Are 3157 and 4157 bulbs interchangeable?
The 3157NALL is a standard filament type bulb with amber coating while the 3157A was high output clear bulb which according to Amazon’s product information is now discontinued.