I don't believe I shared this back in 2020 but what reminded me of it was the other day was the 26th anniversary of the event.
Sachio Kinugasa of the Hiroshima Karp (1965-1977) held the "world" record for most consecutive games played at 2215 & Cal was set to pass that milestone in Kansas City during a weekend series.
My buddy and I flew out to it (Kinugasa was in attendance as well) & during the record breaking game, I was able to obtain a foul ball that Chris Hoiles hit (which is a story in itself).
Another story, but post game we were fortunate to take a shuttle van back to the hotel with Kinugasa & I asked him to sign the ball...He accommodated me by signing it on the sweet spot and added 2215 underneath.
A couple years later I had Cal sign it and asked that he add "2216" underneath as well.
While I've seen baseballs signed by both, I've never seen one that was actually used in that game (as a side note Mr. Kinugasa unfortunately passed away in 2018):
