Thanks to all who mentioned these previously. While not as nice as my Avid Ultimates they get the job done for using 650's in a 26" rim brake frame or fork. Lots of adjustment and easy enough to set up. MMcG, you might be interested in these. I think they can still be found on ebay.
Mtbr's 2016 Winter Biking GearReviews and Roundups
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Thread: FMF brake for 650b conversion