I might look into a metal ring (shaft only though) but more on the thicker side. I consider myself kinda “flat” to, so I don’t know if that will be a problem or not.
I do have a 1.5” black ring, though it’s not rubber, it doesn’t flex and requires some lube to get on. It sure as hell doesn’t look like it can go behind my balls :) so I won’t risk it, but I will see if it treats my erection different since it’s “hard” versus pliable like a rubber/silicone one.
Btw - I posted some more “red lasso” cockring pics over in the member pics area.