Axial wrote:
As commonly available in the stores, these tubes seem to be made of 2
different types of foam, one that is slightly more "rubbery" than the
other.

Update: I bought both to try, but ended up preferring the "rubbery" type
of insulation (it's similar to neoprene; one brand is Rubatex) rather
than standard foam. Pricing for self-sealing type: standard foam 99
cents / 6ft, rubber-type 3.49/6ft.

The rubber-type was much easier to install. It stretched around elbows
so it didn't need cutting, and could easily go around "T"s. It was much
easier to fit around multiple short-segmented areas like up to the
bathroom sinks.

Thx to responders for advice.