I use tech stirrups they're amazing and have helped with my knee and ankle pain so much. I can ride for hours with out getting cramps in my knees
Flex-on. Apparently they should help for knee problems. I don’t have personal experience but that’s what the salesperson told me when I bought mine.
I use Metalab air cushion stirrups and they help my knee/ankle pain so much! They’re pretty pricey but last forever and I’m my opinion so worth it. They have a version with black flexor things on the sides or just plain ones