The Rockwood 441CU Dome Door Stop Combination Unit, Solid Cast Brass with DuraFlex Bumper. Rockwood 441CU Dome Door Stop Is Convertible for undercut or not undercut doors. For use at doors with or without a threshold. Rockwood 441CU Set consists of 1 each No. 441 and 1 each No. 444. For use at doors with or without a threshold. See Manuf Spec's