I bought a set years ago just after completing a job that required various narrow strips of plywood when I was out of the workshop (where I could have used the tablesaw) and the parallel guides would have made that job so much easier.
I think I have used them for a couple of things but cannot now remember what!
I made a nice box to keep them in as they are clunky to store otherwise:
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…and that is probably exactly where they will stay!
TBF they do work well and definitely the most precise way of doing repeat cuts with a tracksaw (well without MFT etc but that is limited to smaller pieces).
Cheers