Awl --

You know the insulation you put on plumbing pipes, either soft black squishy
stuff, or the lightweight hard white-ish/beige stuff, both split down the
side?

Is that stuff available *without* the split?
The use is not plumbing, btw, but rather cushioning, and at times under some
force, so any split along the side is very dicey.

I know it's available from mfr's, but I haven't been able to find it
retail/locally.

If I have to go to a "house" and buy quantity, iny recommendations? And
what is the generic classification of what I'm looking for?
I believe it is "open cell" and "closed cell" *foam* tubing -- correct?
Any other names for this stuff?

--
EA