In Canada we generally call it the sleeve, or the wrap.

I'd understand either of those, but I'd go with "tubing"

	▲	pitaj 5 hours ago \| parent [-]
		That's heat shrink tubing, but we're talking about one of these: [1]: https://www.holley.com/products/engine/engine_dress_up/hoses... [2]: https://www.oreillyauto.com/detail/c/dorman-conduct-tite/lig...