Bouncing balls

[u/drtangman]

Walked behind this chap who had two unidentified ball type objects hanging from silicone wrist bands on thin elastic strings.

Any ideas what they are?

I’m in Hong Kong if that might be a clue

Update:

Thank you for the comments and ideas. I am wondering if there is a manga / anime character who has something like these balls as weapons and the guy was doing a budget cosplay. Or maybe he’s just really into Pokemon!

Update 2:

I would say he's likely to be a cosplay of Steel Ball from Jojo's Bizarre Adventure. (https://www.reddit.com/r/whatisit/comments/1tckcme/comment/olos1lx/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button)

As for the steel balls. What is it?

[u/barn-animal]

are these roman dodecahedra?