Help: Wrap metal duct with Reflectix.

Metal ducts under my house had a fiberglass based insulators that are falling off and now the ducts are sweating. I am planning to install a foil based (Reflectix) insulator coming weekend.
I am thinking a "linear pipe wrapping" approach using 24" wide insulator.
My question is: What is a preferred method to hold the insulators together around the ducts. I can think of staples or tapes....
Thank you for your advice.
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