For those wanting more info, the label on the good stuff says:
armacell
Self Seal Pipe Insulation
Fits:
1/2” Copper, 3/8” Iron
Since it is split completely through (other pipe insulation isn’t), you don’t have to remove the handles from the canning tongs for test fitting or installation.
Tape the handles up enough to provide a snug fit. This is a one-time ordeal requiring less than 5 minutes. Then peel the covering off the split ends of the foam and press them together. Done.
If I were in a rush, I could remove the old foam and cut and install new in less than a minute.
I was concerned at first that the glue may not hold firmly enough, but it’s very robust, certainly the equivalent of contact cement. I tried to pull it apart. The foam rips before the seam separates.