In Canada we generally call it the sleeve, or the wrap.
I'd understand either of those, but I'd go with "tubing"
https://www.3m.com/3M/en_US/p/c/electrical/wire-cable/tubing...
I'd understand either of those, but I'd go with "tubing"
https://www.3m.com/3M/en_US/p/c/electrical/wire-cable/tubing...