Speedi-Boot SBH-888 SRA 8-Inch Width by 8-Inch Length to 8-Inch Diameter Square-to-Round 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