A tip from Burnham...if you are using a adjustable friction saver cinched up tight on a spar, and are planning to bail out to the ground leaving some significant standing stem, there are times when the large ring will snug up flat and tight against the spar and resist your pulling the end of your climb line w/ retreiver through. If this is your plan, put a HMS biner on the large ring and run your climb line through that instead of the big ring. The big ring will lay flat against the spar, and the biner will lay at approx. 90 degrees to that, leaving an unrestricted opening to pull your rope and retreiver through.
Can cut down on doing a bunch of rope flapping and pulling to get the FS free.