TerraBloom 6 Inch Duct Clamps for HVAC, Flexible Ventilation Ducting, Air Hoses and Inline Fans. 2 Clamps Per Package. Stainless Steel 6 INCH CLAMP FOR 6 INCH DUCTS: Our clamps provide 25mm slack to comfortably fit over 6 Inch ducts EASY INSTALL AND ADJUSTMENTS: These clamps can be installed and tightened using just a screwdriver 2 CLAMPS PER PACKAGE STURDY STAINLESS-STEEL CONSTRUCTION INDOOR GARDEN AND HYDROPONIC USES: These clamps will help to create air tight connections between inline fans and carbon filters or air cooled light fixtures, as well as secure intake and exhaust air lines