How to pick the brake cable housing size? I am trying to buy new brake cable housing for my road bike, but got confused about the sizes. I was going to go for this one (5 mm diameter). Which should nicely fit around a 1.6 mm brake cable.

However, Googling a bit further revealed there are also 3 mm, 4.9 mm or 5.5 mm diameter variations available.
Is there any difference in functionality and performance between these sizes?
Google search hits for reference:

Note: the question is similar to this one (What is the difference between brake cables and derailleur cables?). But there is no information about brake cable housing size in there.
5mm is the standard for bike parts made since I don't even know when, 1940s-ish.
6mm was an early MTB thing and is found on some 80s brake parts and frame housing stops. Don't worry about it unless you're working with a vintage mountain bike with overtly chunky housing and cables.
5.5mm is confusing the way a few manufacturers toss the number around. Basically, some special kit-type brake housings use it, typically braided or those with a braided outer, and they also need their own special ferrules, which will come with the housing anyway. There are no frames or parts that need or are designed for 5.5mm.
3mm isn't a thing.