Talked to a few local bike mechanics, and those rings are from the pin, not the chain. They were sheared off during the removal process(they're the outer bits of the pin that make it hard to push through the chain, and hold it in place). At some point, the fatigue is enough to break them off, so that's why you'll sometimes have them accumulate on the driving pin. Coincidentally, this is another reason it's not recommended to reuse the pin you removed.

Those medal shards are from the chain not the pin and it’s common on all chain tools.

Had axpark tool ct-5 do thexsame thing the cheap tool you showed did. Had my ct-5 fail and park tool refused to warrant it. They ignored the details of the warrabty claim and claimed itcwas user error. (Been fixing my own bikes and buikding them for over 15 yrs!) Slways boughtvpark tool. Not feeling very confident in them after that!

I look forward to more reviews like this 👍

Thanks for getting in there and looking at whether the pin was straight...I was concerned about this seeing as I just finished a chain job and destroyed a cheap chain tool with a crooked pin.

had similar experience with white lighting branded chain tool damaging a chain. After $10 for the tool, and $15 for a new KMC Chain to replace damaged one the compact Park Tool One would have just been cheaper. The chain tool on my knock off crank bros multi tool worked much better. Probably going to bite the bullet and get the full sized park tool one.

will this work on 12 speed chain ?