The Herdim String Lifter (or bridge jack for cello) is a handy tool for changing bridges.
This tool works great. Weather caused changes to my cello fingerboard height require me to change bridges 2-3 times a year. With this tool I can change the bridge without worrying that the sound post will fall down. Saves me emergency trips to a luthier. It also helps me position the new bridge to the same place as the old bridge.