Two locations that offer the parts for metal ductwork installation are Lowe's and Home Depot. Both stores offer everything needed, from the ductwork itself to tools and accessories. Both stores also offer local retail outlets and the ability to order parts online.
Even though brand names may differ, both Lowe's and Home Depot tend to carry the same wide range of inventory necessary for ductwork installation. This offers installers a choice of parts to use, easing the installation process.
Both shops offer sheet metal duct parts and parts needed for flexible ducts. Sheet metal ducts are generally used for in-wall ductwork, running the full length of a structure to provide heating and cooling throughout. Flexible ductwork is typically used in tighter spots, or for shorter runs; for example, when installing ductwork to vent a dryer to the outside of a structure.
To find specific parts on each of the sites, general search tools are provided. The sites also offer filtering to help narrow down choices after searching or to aid in browsing the sites. At Lowe's, filtering is by price, brand, materials and even the size of the ductwork. Home Depot includes the same filtering options, but adds category filtering as well.