Galvanized sheet metal cleats are used to join and secure sections of rectangular ductwork together at the seams. D cleats and S cleats are the two standard types used in residential and commercial duct assembly. D cleats (drive cleats) are used on the short sides of the duct joint; S cleats (slip cleats) are used on the long sides. Sold in 5-foot lengths. Essential for proper duct assembly per SMACNA standards.