Bertech High Temperature Polyimide Masking Discs are made of 1 mil thick polyimide film with 1.5 mil thick silicone adhesive. These masking discs are reliable and durable with a unique combination of electrical, thermal, chemical, and mechanical properties that withstand extreme temperatures, vibration, and other demanding environments. They are packaged on a 3 in. core. Custom sizes are available upon request. RoHS Compliant.