"套管式伸缩的" can be translated as "telescopic with a casing" or more specifically, depending on the context, "casing-type telescopic".
"Telescopic" refers to something that can be extended or contracted in length, like a telescope.
"With a casing" or "casing-type" specifies that the telescopic mechanism is enclosed or protected by a casing, which is characteristic of certain types of伸缩（telescopic or expandable）devices, such as in some engineering or mechanical applications.
For example, if you're talking about a casing-type telescopic joint in piping systems, you might say "casing-type telescopic joint".