Self-amalgamating tape is a non-tacky silicone-rubber tape which when stretched and wrapped around cables, electrical joints, hoses and pipes combines or unites itself into a strong, seamless, rubbery, waterproof, and electrically insulating layer. Unlike many other polymers and fibers, it is heat-, sunlight-, and weather-resistant. This type of tape is also described, particularly in the United States, as "self-fusing", or "self-vulcanizing". In the US Air Force (and elsewhere) it is called centerline tape due to a colored line running down the center used to assist with even wrapping. It is also called "F4", "tommy", "rescue", "Tape 69" "magic tape", and "fix-it tape".