wrote in message
oups.com...
I've noticed two different types of these; some are apparently made of
brass and have a completely rounded external profile, whereas others
seem to be copper, and have flat chamfers at either end.
Can anyone tell me the significance of the two species, and are they
interchangeable in different compression fittings?
I wondered about that. A lot of the fittings from the plumbers merchant
come with copper ones for some reason, but you can only buy copper ones
in large quantities and the sheds only seem to have brass ones.
Brass are harder, and apparently give more support to the pipes.
Copper are softer, and seem to require less tightening.
I'm sure both should work OK.

I think copper ones are ok on plastic (with the insert) but not brass these
are too hard