Generally, there are two main rims to choose from:

Box section, which is something like this. M13II falls into this category.


It's rather square and not as "protruding" as the other type, which is deep section or aero rims. Like DP-18, Deep Vs, B43, H+Son 42cm, etc etc.


The are generally at least 30mm in depth and it go up from there.

In my opinion, box section wheels look better on steel bikes because their tubings are usually look slimmer than aluminium or carbon fibre bikes.