Speedi-Boot SBH-4127 SB 4-Inch Width by 12-Inch Length to 7-Inch Diameter Straight Register Vent Boot with Adjustable Hangers Adjustable telescoping hanger arms that can be shortened as well Foam gasket seals air tight at installation to back of sheetrock Dust and debris cover preventsconstruction contamination Mud ring prevents gaps between the boot and sheetrock Dust and debris cover provides a plug for HVAC pressure testing