Nitto P-421 is a 5 Mil PTFE film tape. P-421 is a heavy-duty tape that fulfills requirements for an ultra-high dielectric strength, high temperature use with high to medium gauge magnet wire in larger-size components. Impervious to most chemical attacks, including acids, solvents, fuels and most alkalies. - PTFE backing provides low coefficient friction, which makes for a slick surface that promotes the quick movement of materials. Cured silicone adhesive enhances P-421's ability to operate over a wide temperature range.