ShurFLEX HVAC printed professional grade metalized cloth duct tape for use in the HVAC industry to seam, connect, splice, patch and seal sheet metal and flex duct, insulation, rigid ductboards, air vents and fiber board. SF 683 is designed in color and appearance to match sheet metal, flex duct and ductboard, is hand-tearable, and delivers an airtight and moisture-free seal.