The A refers to the bulb shape. A is for arbitrary and is the shape that we all think of when we envision a light bulb (C is for candle, G is for Globe etc.) The number 19 designates the size.

Five years ago I bought my first LED light bulbs. They were to replace halogens in my bathroom. I spent too much money on not enough lumens and way too many kelvin. You know what I mean? No? Perfect.

Buying a light bulb is a little more complicated than it used to be. You can't just pick up a similar watt bulb and expect it will match the other bulbs in the room, or even work in your fixture. So ...