The microscope holding arm works GREAT.
One tip - if you're not using it with one of the specified (30 or 35mm) diameter
microscopes, then the latching hoo-hah won't work. Bigger OR smaller - the
latch won't close or hold (eg. a "Firefly" microscope - high end, for sure, but
they make 'em with special lighting)
The fix, however, is simple. Take the whole mess to your local plumbing supply
store and get an O-ring of the right size to give you a nice springy grip (or if you
happen to have an O-ring "kit" then you're all set.)
Or, if you're really "ghetto" - use a rubber band. But the O-ring looks nicer.