FYI. (even though the thread is 3 yrs old)
They’re called Warendorf reins. And also FYI, they are on backwards in the original photo. Ring should be facing outward, leather inward.
I have a few. Love them buut you might get some grief from (uneducated) officials in dressage who will say they have a “gag action” - they don’t.
They’re older so not a lot of people see them. They’re also a PITA to keep clean and over-time the ring will damage & weaken the leather, so buckle or hook-stud reins are really a better investment long term.