They are all made from mugs but some mugs have rubber grippies that protrude through the sides. When you remove the grips, the holes are left.
With these smaller stoves I have been using a continuous windscreen with no gap (for handles) that either rests on another type of clip mount or on a clip and wire stand that can be inserted in the ground. This works extremely well and is easy to add and remove while burning.
It sure is a nice added plus that the grippies have left you some tactical looking air intake holes Nice choice!!!
The windscreen with the opening allows twigs to be feed in the side port, right?