Jim Lux wrote in
:

....
Yes indeed.. they're hard and brittle.. Drop one of those 2.4" toroids
off a ladder onto a concrete floor, and they break.

Or, put two of them loose and with not protection in the post.

Actually, the easiest way I have found to chip them is to thread them on
coax for a W2DU balun, and let them fall just a couple of inches (hang on,
we are metric, that would be 50.8mm).

Owen