How to figure out the light bulb part number?

I have done quite a bit of research and still can’t figure it out, so I feel stupid about this. I have also failed to take out the particular bulb myself, so I can’t see back of the bulb. I need to buy one so I can bring to the repair shop.

I have a 2008 Volkswagen Jetta, and one of the headlight bulbs is out. There are two low beam bulbs, and one high beam in total on each side. I know that the low beam on the outer part is H7, and the low beam bulb on the inner part of the headlight looks smaller. But for some reason, looking at Philips or car parts websites, I can only find H7(regular low beam) or 9006 which seems to be the fog light. So how can I figure out the part name or number for that small low beam bulb?