I am finishing our basement with drywall. Can we is use this to insulate the metal ductwork that we are boxing around with drywall.

You can use the Reflectix on the duct work. You would need to cut 2" wide strips of the product and wrap them like a band around the duct work every 18inch - 2ft. This allows an air space between the duct and the Reflectix product. Then wrap the duct with Reflectix and tape the seam with foil faced tape. This application will yield an R-value of 6 and help eliminate condensation.

Dear Donna: Reflectix and similar reflective / radiant barrier products are not effective. The shiny bubble wrap only provides R-1. You must build a sealed air gap around your ducts; this air gap actually provides almost all of the claimed R-value. Fortunately, Lowes sells a better solution: fiberglass duct wrap. See: Frost King, Lowes Item # 179375 Model # SP55. Use foil HVAC tape to seal the edges -- not silver fabric "duct tape". See: 3M, Lowes Item # 350444 Model # 3340. In addition, you can simply pack insulation around your duct and fill the chase you are building around it. Roxul rock wool is the best option, with R-4 per inch. See: Lowes Item # 138683 Model # RXCB351525. Before you install the insulation, however, make sure your ducts are sealed to block air leaks. Simply slather on a layer of mastic with a cheap paint brush or glove, over every joint. See: Design Polymerics, Lowes Item # 408056 Model # KK0326. I hope this is helpful.