Where is the properties for static mesh?

I feel really stupid but I’ve been banging my head against UE4 for almost an hour trying to set my mesh to per-poly collision.
I know I have to change collision to “use complex as simple” but I can’t find that option anywhere.
There is no “Properties” under the right click menu and nothing like that under the “details” panel.
I feel that I must me missing the trees for staring at the forest.
Please help.

Naturally I find it after I post this.
It’s in the Mesh editor.