Professional results that a DIYer can be proud of begins with 300 Heavy-Duty Duct Tape by Nashua. This duct tapes durable PE-coated cloth backing conforms well to irregular surfaces and resists twisting and curling. Measuring 10 mils thick, Heavy-Duty delivers maximum durability and adhesion, perfect for any project, job or application. Nashua Tape. Trusted by professionals. DIY approved. Count on Nashua to get the job done right. Color: Grays.