In Canada we generally call it the sleeve, or the wrap.
replyI'd understand either of those, but I'd go with "tubing"
replyhttps://www.3m.com/3M/en_US/p/c/electrical/wire-cable/tubing...
That's heat shrink tubing, but we're talking about one of these:
reply[1]: https://www.holley.com/products/engine/engine_dress_up/hoses... [2]: https://www.oreillyauto.com/detail/c/dorman-conduct-tite/lig...
For performance vehicles I used adhesive-lined heat shrink tubing for basically everything.
reply[1] Braided tubing and [2] conduit, respectively.