Twalcom and Wunderlich do them, they're exactly the same. Got mine from adventure bike warehouse, don't know if they still have them. I think Nippy Normans sell the elliptical ones.
If you're fitting them to the F8 you may have trouble folding the right had one in all the way due to the brake reservoir, mine are on z-technic mirror extenders , which push them forward slightly so I can fold them all the way in.
I've seen some that are like tis but are extendable... Google is your friend.