World's best hanger strap. Hanger has 1 in adjustment button holes. For 2 in x 8 in Joist, material locks to 1 in roofing nail (button) when pulled down. For 7/16 in particle board, material locks to NO 8 sheet metal screw (button) when pulled down. 2 in HDPE Duct Board Hanger supports 50lb per strap. 100 ft Rolls Also use Saddles with 2 in Thermo Button-Lok™ as extra support for square duct board.