I put an older campag super record 11 crankset in a 2015 cannondale synapse carbon with a bb30a bottom bracket. There was some play. It rode alright, but was hard to keep a consistent chain line, so shifting was occasionally poor, and i got some creaking and clunking from time to time. I tried to come up with a solution from home bench, including pulling the bearing cups, and putting a 42mm inner diameter spacer between the cup and the frame (not a great idea).
Then I found this shim kit, ordered it, problem solved! After tinkering with different combinations, it turned out I had approx. 1.63mm of play to correct. No more inconsistent chain line. No more creaking or clunking. Great product, highly recommend! This bike is MUCH more pleasurable to ride now