Basement ceiling duct metal
The screws will run in without pre-drilling. Depending on the gauge of the metal, you may need self tapping screws however. They have a small drill point on the end (available at HD & Lowes). How much of a span are you trying to go over?? You may not need to attach to the duct work. If you're spanning 16" or less with 1/2" or 24" with 5/8", no need to screw to the duct.
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