The only stability leathers I have are the Millbrook ones.
The first time I touched the leather I knew that these leathers might actually be usable (if taken care of) after I die (I’m in my late sixties.) The regular stirrup leathers had become wimpier over the years, prone to twisting easily and never giving me the feeling of stability that I get with the Millbrook leathers.
In my life I had one pair of the calfskin covered leathers, and I will never buy a pair again (they came with a saddle.) These wimpier leathers were not comfortable to my legs, if I dropped my stirrup I had to check the stirrup leather when I picked up my stirrup again because it had often twisted, and bony growths started on my shin bones where the stirrup leathers crossed my leg.
After a year or two of not using the wimpy leathers my shin bones still have little lumps where they crossed my shin, at least with the wider leathers my shin bones started to reabsorb the bony lumps which shrank. The wimpier leathers hurt so much more to ride in than the older types of substantial hunt seat leathers I started with almost 50 years ago.
I am SO HAPPY riding in my much more substantial Millbrook leathers, and I will probably never switch back to “normal” English stirrup leathers.