I immediately thought about the hardware they use on school and RTD buses & trains for the hand rails. No idea who makes it, though if you spoke Chinese it might help to call them.
'91 Toyota Pickup
'09 Kawasaki KLR650
'12 Gunnar Rockhound 29
"They say the test of literary power is whether a man can write an inscription. I say, 'Can he name a kitten?'" -- Samuel Butler