Flexible duct hanging strap which attaches to buildings, it should be used in conjunction with a hanging saddle
Round Duct Strap Bracket - Ductmate Industries
Duct Strapping Hanger
Duct Fittings
Hangers/Straps/Ties
Refrigeration
Heating & Cooling Componentry
Hangers/Straps/Ties
Master Flow 1.75 in. W x 100 yd. Woven Vinyl Hanger Strap HS1.75WV - The Home Depot
Duct Straps and Hangers
Hanging Rectangular Duct with 1″ wide Hanger Strap - Conklin Metal Industries