Do you know what’s difference between 4157K and 4157 bulb?

I try to answer you as below.

4157K bulb is almost the same as 4157 bulb because they are same base.

The only difference between 4157k and 4157 is inside gas.

4157k put halogen gas inside bulb, but 4157 isn’t gas in there.

Why we need to put gas inside 4157k bulb?

Because halogen gas can help 4157k increase their life time.

At the present, are you clearly now about 4157k and 4157?

Welcome customers come to talk about 4157k and 4157 at any time.