I have a split system located in my crawl space. The vents consist of one main large metal tube with insulation on it. The branckes to the floor registers are flex. Over the years I have had cats and animals get under there and tear the flex.

Is it better to go all metal ducts? Can I wrap regular insulation around them?

Is there a sleeve or some other protective thing like pipe insulation I could use over the current branches?

I appreciate it!