I used to a long time ago. I got a set when I was in Korea, but apparently my wonderful ex-wife lost them, along with half the rest of my crap, when we got divorced.
I can do clockwise without them touching on my right hand and the same when going counter clockwise on my left hand. But I'm still working on counter clockwise and clockwise respectively.
My mum has some in one of the cupboards somewhere, what the hell are they even for? I've never known.. not like I bothered finding out either, but I'm hoping to get a reason here XD
They're used in cases of damage to the hands in physical therapy, and by people who just want to increase their hand strength and dexterity. They say they're supposed to help in stress relief but considering by gray hairs, I doubt that's valid