Professional results that a DIYer can be proud of begins with 324A Premium Foil HVAC UL Listed Tape by Nashua. This foil tape is UL coded approved for sealing class 1 rigid (181 A-P) or class 1 flexible (181B-FX) duct joints and connections. With a heavy-duty foil backing that is printed for easy inspection and an aggressive acrylic adhesive, Nashua 324A is the ideal choice for heating, ventilation and air conditioning installations that require a code-approved product. Nashua Tape. Trusted by professionals. DIY approved. Count on Nashua to get the job done right. Color: Metallics.